After you become Champion and upgrade your Mega Ring, you will get a mission from Looker in Lumiose City.
To start the Looker Sidequest, first you have to defeat the Elite Four and Champion. Then go to Lumiose Station in North Boulevard of Lumiose City. Talk to Professor Sycamore to get the TMV Pass. Use it in the orange ticket machine next to the train.
When you arrive in Kiloude City, go to the Battle Maison and win at least one battle. You can interrupt the challenge after that. Go to the north part of town to find your neighbor. If your neighbor is not there, leave town and go back in, then check the north part of town again.
Talk to your neighbor to do battle. Afterward, your neighbor says to meet Professor Sycamore at the sundial of Anistar City. After you talk to Professor Sycamore there, go to Lumiose City and walk around. You should get a Holo Clip from Looker. If not, leave Lumiose City and go back in, then walk around until you get the Holo Clip.
First, Looker asks you to go to the Looker Bureau. It's near Rouge Plaza and is across from Sushi High Roller. To get there quickly, Fly to the north part of Lumiose City, then go into the street next to the northern Lumiose Pokémon Center. The Looker Bureau is on the right.
When you arrive, Looker asks you to be his assistant. Before you can do that, you have to take lessons in spying techniques. Talk to him again when you're ready.
He'll ask you to find the five Looker Tickets hidden around Lumiose City. The notebook on his desk in the back of the room has hints on the locations. You'll also get a Holo Clip from Looker when you leave the Looker Bureau that lists all of these locations.
The first ticket is in the central Pokémon Center. You can just fly there by tapping the center dot of Lumiose City, or you can go to Prism Tower and then ride around Centrico Plaza looking for the pokémon center in one of the side streets. Inside the Pokémon Center, check on the sparkles on the floor to get the ticket.
Go into Prism Tower, which is in the center of town. Check on the sparkles on the floor to get the ticket.
This one is in the Herboriste shop. It's on Vernal Avenue. It has a sign in front of it of a vase with herbs in it. Go inside, then check on the sparkles on the floor to get the ticket.
This ticket is in the Hotel Richissme on North Boulevard. The Hotel Richissme is a black building that has a Skiddo sleeping nearby out front. Go inside, then run around the lobby looking for sparkles on the floor. Check on the sparkles on the floor to get the ticket.
This ticket is in the Lumiose Museum on North Boulevard. The museum is a white building with columns out front. Go inside, then run around the first floor looking for sparkles on the floor. Check on the sparkles on the floor to get the ticket.
After you find all five tickets, go back to the Looker Bureau. You can find it by going into the side street next to the Pokémon Center on North Boulevard. When you talk to Looker, you should agree to become his assistant. He mentions a case that he has been trying to solve. He says he'll send you a Holo Clip when he has a new job for you.
Walk around town until you get the Holo Clip. Looker asks you to go back to his office. When you go back to his office, Looker asks you to read the notes on his desk about the case.
The case is from a concerned mother from Lumiose City who is worried about the suspicious kids hanging out in the back alleys of the city. Looker asks you to start by visiting the alley leading off of South Boulevard. He makes a note of all of the alley locations. Check the notebook for details about the alley locations.
Go to South Boulevard. The alley is next to Restaurant Le Nah. In the alley, there are kids blocking the way. You have to defeat each one in battle before they let you pass.
First is Preschooler Natalie, who has a level 53 Swinub and a level 53 Bonsly.
Next is Preschooler Lily, who has a level 55 Igglybuff.
After that is Schoolgirl Callie, who has a level 53 Rapidash, a level 53 Leavanny, and a level 53 Kingler.
The last trainer is Schoolboy Macon, who has a level 56 Spiritomb.
After you defeat the trainers, Looker arrives, and you discover an Espurr called Mimi, along with a girl dressed in rags who has befriended Mimi. The girl can't afford Poké Balls, so Mimi just runs free. Looker says that since he lives in a hotel, the girl can live in the Looker Bureau if she becomes his assistant.
Looker asks if Mimi likes the idea, but Mimi gets scared and runs off. The girl says she was initially happy about the idea of having a place to sleep at night, but since Mimi didn't accept it, the girl rejects the offer. Looker asks you to try to befriend Mimi.
Leave the alley. You'll get a Holo Clip from Looker, who says that Mimi doesn't like to be petted. Mimi is known to go to the following alleys:
To get to North Boulevard, turn left from the exit of the alley where you met Mimi and the girl. The first alley that you reach is the one across from Lumiose Station. If Mimi is not there, turn left after exiting the alley, then look for the Galette Stand on the right. The alley is actually across from the office building next to the Galette Stand. If it's empty, turn left after you exit the alley, then look for Café Triste on the left and go into the alley just past it. There's a woman in a green dress looking into the alley.
When you do find Mimi, talk to it. The correct option is Dance. If you choose the wrong option and Mimi runs away, look for Mimi in the other alleys.
Afterward, the girl agrees to become Looker's assistant. The girl's name is Emma. Later, Looker worries to himself that he might not get enough cases to keep food on the table.
Walk around Lumiose City until you get the next Holo Clip from Looker. He asks you to return to the Looker Bureau. He says that Emma seems stressed out, and he's worried that his attempt to be her guardian is burdensome to her.
Later, a woman in a green dress runs up and says something in another language. In the English version, she speaks Japanese. (In the other language versions, it seems that she speaks English.) Looker thinks that she is asking to be served tea. He runs off.
Emma and Mimi return. The woman says more in Japanese, and it turns out that Emma understands the language. She and the woman exchange more words, then Emma asks Mimi to use its mystical power. This allows you to temporarily hear Emma and the woman's thoughts.
You learn that the woman's pokémon were stolen when she was in Lumiose Station. Looker returns. Emma doesn't want to help because she believes that the Lumiose Gang is responsible, and she doesn't want a big battle. Looker says it's important to help those in need, and runs off to the station.
Emma begs you to go help him since he doesn't even have a pokémon. Apparently he used to, but they were in a battle and the pokémon didn't make it. Agree to help Looker.
The station is on North Boulevard, so turn left after you leave Looker Bureau to reach North Boulevard. The Pokémon Center is to your right, so go in and heal up your pokémon if you need to. Then turn right and go along North Boulevard until you see the two red-skirted girls who stand in front of the station. Go inside.
Walk east along the platform in front of the train until you find Looker and a punk girl at the end of the platform. The punks are upset that Emma stopped hanging out with them after moving into the Looker Bureau. The punks stole the pokémon to make Looker challenge them. The punk says that if Looker wins, they'll return the stolen pokémon. If Looker loses, he and Emma must part ways. Looker says he can't accept the challenge because he doesn't have pokémon, but he and the punks see you standing there, and the punks say you can fight them in Looker's place.
The punk girl to the right of Looker is Lumiose Gang Member Sedna. She has a level 58 Mandibuzz.
The punk girl to the right of Sedna is Lumiose Gang Member Eris. She has a level 56 Pangoro and a level 56 Bouffalant.
The punk guy is Lumiose Gang Member Nix. He has a level 56 Druddigon and a level 56 Krookodile.
After you defeat them, Emma arrives and makes them agree to give back the tourist's pokémon. The gang agrees to give up their criminal ways and do honest work. Emma expresses concern about Looker's finances, but he assures her there is no need for concern. However, Emma decides to look for a part-time job.
Walk around the city until you get another Holo Clip. Looker says that something is wrong and asks you to come to the Looker Bureau right away. He says Emma has not been there lately.
Then you get a Holo Clip that someone broke into the Lumiose Museum last night and damaged a painting. Looker has an appointment so he can't check it out and he asks you to go. Turn left after you leave the Looker Bureau, then turn right on North Boulevard. The museum is the first building on the left.
Inside, a painter near the entrance says that the graffiti is on the third floor. Go up and talk to the museum director, who is standing in front of the graffiti. Then after you talk to the museum director, leave the museum. You'll get a Holo Clip. It says that Poké Ball thefts have been occuring in the back alleys by thieves who steal the Poké Balls after battling a trainer. After this, you get a Holo Clip from Looker, who asks you to return to the Looker Bureau right away. Turn right, and go into the side street to the right of the Pokémon Center. Looker Bureau is on the right.
Talk to Looker. He says that you should trick the thieves into trying to steal your pokémon by battling them while Looker hides in the shadows, ready to capture them when they try to steal your pokémon after the battle. Looker says to go to the alley near the Galette Stand. When you leave Looker Bureau, turn left, then on North Boulevard turn left again and go into the first alley on the left.
At the end of the alley, talk to the woman to battle her. She is Supsicious Woman "???" and she has a level 58 Jellicent and a level 60 Volcarona.
After the battle, she attempts to steal your pokémon, but Looker runs up and stops her. She transforms and is shown to be wearing a suit of some kind, then runs away. Looker says to check the alley next to Café Triste. Looker heals your pokémon first.
When you leave the alley, turn left. Go into the alley where a woman in a green dress is standing. In the alley, you get a Holo Clip from Looker, who is ready to provide backup.
At the end of the alley, talk to the girl. It's Suspicious Child "???" and she has a level 57 Whimsicott, a level 57 Mawile, and a level 57 Granbull.
The girl transforms again, and runs away. Looker says to check the alley across from Lumiose Station. When you leave the alley, turn right. Go into the alley across from where the two red-skirted girls are standing in front of the station.
This time you find a Black Belt whose Poké Balls were stolen. The thief went to the alley in South Boulevard. There is only one alley there. When you leave this alley, turn right. When you reach South Boulevard, go into the first alley on the right, near the sleeping Skiddo.
Talk to the girl in the alley. It's Suspicious Lady "???" and she has a level 60 Persian.
After the battle, the lady once again transforms. Mimi the Espurr runs up and is friendly to the person, and Looker is convinced that the person is Emma. However, the person calls herself Essentia. Looker tries to reach out to Emma, but Essentia beats him up, after which Essentia seems to malfunction. Then Essentia runs away.
Back in Looker Bureau, Looker says that he will go to the hospital and tells you to take the day off. Afterward, you see Looker asking Mimi to give you something. He says he will not actually go to the hospital, but will instead seek help from an unpleasant source, knowing that Emma was turned into Essentia by "that man".
Walk around Lumiose City until you get a Holo Clip. It's from Emma, who asks you to meet her in Looker Bureau. She wants to meet Looker. When she learns that he's in the hospital, she realizes that she doesn't have enough money to get there, and then she sees that it's late and she has to be somewhere. She runs off.
Then a man comes in with a request. First he asks to battle you. He is Butler Chalmers, and he has a level 62 Braviary.
After the battle, he says that he was once a Team Flare Admin and was sent by his mistress to test you. He says that you must hurry to Hotel Richissme to the Royal Suite and meet his mistress before she gets impatient.
When you leave Looker Bureau, turn left to go to North Boulevard. Then turn right and go into the black building after the museum. There's a sleeping Skiddo near the entrance.
In the hotel, use the elevator to go up to 5F. Go south from the elevator, then go into the room on the left. You will find Malva, the Elite Four member who focuses on Fire-type pokémon. She has the level 63 Pyroar that she used in the Pokémon League.
After the battle, Malva reveals that Essentia really is Emma. She's wearing a suit created by Xerosic called the Expansion Suit. Malva was once part of Team Flare herself, and she wants you to make Xerosic disappear so he can stop tarnishing Team Flare's honor and so Emma can stop committing crimes as Essentia.
Malva tells you to find Xerosic at Lysandre Café, but tells you to prepare well or you might face death.
To get to Lysandre Labs, first go to Prism Tower, which is in Centrico Plaza. Then ride around Centrico Plaza looking for the Pokémon Center in the side street. From there, go into Magenta Plaza (where there is a small monument) and turn right to find the small street with Lysandre Café.
Malva is already there and asks you to follow her. In the main room of the lab, she'll enter a password on the elevator so you can go to the hidden floor where you'll find Xerosic and Essentia.
Go into the elevator and choose Hidden Floor. Just as Malva said, this floor has the same layout as the first floor. When you leave the elevator, Scientist Sonia battles you. She has a level 60 Elgyem and a level 60 Klinklang. If you talk to her after the battle, you learn that the Lumiose Gang is working for Xerosic as security guards.
Step on the left arrow to the left of the scientist. Then step on the green warp circle in this area. In the next area, go north and step on the green circle on the left. After that, step on the arrow tile north of you.
You end up near Scientist Ernst. He has a level 61 Weezing and a level 59 Heliolisk.
Use the arrow south of the scientist. Then use the arrow south of where you end up. Go east and step on the arrow that points to the right. When you stop, step on the arrow to the right of that. You end up near Lumiose Gang Member Sedna. She has a level 62 Mandibuzz.
Step on the arrow to the left of Sedna. Go southwest and you will walk past Lumiose Gang Member Eris, who has a level 60 Pangoro and a level 60 Bouffalant.
Step on the green circle to the left of Eris. You will end up near Scientist Justus. He has a level 62 Muk.
Step on the green circle near the scientist. You end up in front of Lumiose Gang Member Nix. He has a level 59 Druddigon and a level 61 Krookodile.
After the battle, Nix tells you to follow him into the room he was guarding. Check on the Poké Balls. They were all stolen from trainers.
Now check on the left side of the blue bookshelf in the back of the room. You find Xerosic's notes about the Expansion Suit. You learn that the Expansion Suit enhances physical power, hacks into Poké Balls, disguises the wearer, and allows someone to remotely control the wearer.
Check on the left side of the bookshelf below that. You'll see the first volume of the notes about the Expansion Suit testing. Xerosic posted an ad for a part-time job in Lysandre Café, which apparently Emma replied to.
Check on the left side of the bookshelf below that. You'll read volume 3, which is about Emma replying to the part-time job ad. She didn't really understand what Xerosic's research was for.
Go down the short flight of stairs in this room and check on the right side of the top-left bookshelf to read volume 3. It says that Xerosic tried teaching Emma how to be a pokémon trainer, but Xerosic's pokémon just wanted to play with Emma.
Now check on the right side of the top-right red bookshelf. You'll find volume 4. Xerosic tested the suit by having Essentia break into the museum and put the graffiti on the mural.
Go down to the red shelf below that, and check on the right side to read volume 5. Xerosic had Essentia steal Poké Balls to test the Poké Ball Jack's hacking capabilities, but Essentia ran into you, the Champion, and there was a glitch in the remote control function.
After reading all of Xerosic's secret notes, talk to the punk. A bell rings, which means that his shift is over. He leaves, and asks you to close the place before you go.
When you go toward the exit, Xerosic appears. He wonders if he has to suppress Emma's spirit in order to avoid more remote control glitches, but he thinks it would put too much of a strain on her mind. Xerosic realizes that you are the one who interfered with the trials, so he intends to make you the next Expansion Suit test subject.
Essentia appears, and Xerosic tells her to battle you. Go talk to Essentia to battle her. She has a level 64 Jellicent and a level 66 Volcarona.
Afterward, Xerosic tells Essentia to continue battling. Go talk to her again to do another battle. This time she has a level 63 Whimsicott, a level 63 Granbull, and a level 63 Mawile.
After that, Xerosic tells Essentia to keep battling again. Talk to her to battle. She has a level 66 Persian.
After this, Mimi the Espurr comes in, then Looker. After Looker fails to get through to Emma, Mimi breaks through Xerosic's remote control and causes the suit to malfunction.
After this, battle Essentia once more. She has a level 68 Crobat and a level 70 Malamar.
After this, Xerosic turns off the remote control, and Emma wakes up, not aware of anything that just happened. Xerosic says that the testing is over, so Emma's part-time job has come to an end. Looker tells Emma to get ready to go to dinner together with you and him. Afterward, Looker talks to Xerosic in the office. Xerosic says that he alone is responsible for the crimes that he made Essentia commit. He'll come quietly for his arrest. But since Emma is fond of Xerosic, Looker wants all of them to have dinner together before Xerosic's arrest and before Looker explains to Emma all that happened.
After the cut scenes, walk around Lumiose City until you get a Holo Clip. It's from Emma, who says to return to Looker Bureau because she has some big news to tell you.
Emma says Looker is going to come home from the hospital now. But then Mimi comes in with a letter from Looker. The letter is a confession from Looker that he is actually a member of the International Police. Now that he has closed the case, he has to leave the Kalos region. He bestows up on you the code name of Looker, and he tells Emma and Mimi that he bought the whole building, so she and Mimi can live there rent-free from now on.
Emma is in shock. She runs out of the building to try to stop Looker. When you try to leave, a punk comes in and asks what's going on. When you try to leave, the punk says that he ran into Looker at the Lumiose Museum.
When you leave Looker Bureau, turn left. When you get to North Boulevard, turn right. The Lumiose Museum is the first building across the street.
Go into the museum and go up to the third floor, where the graffiti was. The museum director says that Looker just left. Leave the museum. Outside, you get a Holo Clip. Emma says that Xerosic is with Looker in the Lysandre Café.
To get there, you can go to Prism Tower, which is in Centrico Plaza. Ride around Centrico Plaza and look for the Pokémon Center in a side street. Go into that street, go to where the monument is in Magenta Plaza, and turn right to see the side street where Lysandre's Café is. Go inside.
Watch the final cutscenes to see the end of the Looker Sidequest.