After you pass through Route 2, you reach Verdant Cavern, where you will undertake the Trial of Ilima.
Trial of Ilima
The goal of the trial is to defeat three of the Pokémon in the dens in the cavern, then take the Z-Crystal from the pedestal at the end of the Cavern. You will also need to defeat a Totem Pokémon.
Look inside the nearby den that you saw a Yungoos jump into. You will battle the Yungoos.
After you defeat the Yungoos, go to the right and get the Super Potion.
Go upward and check on the rock in the middle to get a Revive.
When you approach the next den, a Yungoos comes out. Defeat it. If a sparkle appears after the battle, check on it to get an Oran Berry.
Go up the ramp to the left. When you get to the top, go downward to find TM31 Brick Break.
Now go upward and cross the wooden bridge to the right. Keep going to the right, past the den that you saw something come out of a moment ago, and go up the ramp on the right and check on the hole at the top. Get the Super Potion there.
Go to the left to go down a one-way ledge. Check on the nearby den. It's empty, so go downward, then to the left, then up the ramp. Go to the right and check the den there, but it's also empty, so go to the left and go past the guy in front of the cave exit. Go down the one-way ledge, then go past the den and get the X Defense. Then check on the den. It's empty as well, so go down and jump down the one-way ledge, then go to the right and cross the wooden bridge again.
Team Skull shows up. The Team Skull Grunt who battles you has a level 11 Drowzee. You get 352 Pokédollars for winning.
Now go to the right and go up the ramp, and crawl through the hole at the top, then go to the left and check on the den. A Gumshoos will come out.
After you defeat Gumshoos, go downward and jump down the one-way ramp, then go to the left and go up the ramp. Go to the left and talk to the guy in front of the cave exit. He will let you go through.
Defeat the Totem Gumshoos
In the next room, go straight ahead and check on the pedestal. Take the Z-Crystal, and a huge Totem Gumshoos will appear. During the battle, Totem Gumshoos might call Yungoos into battle. Even if you defeat Totem Gumshoos first, you will still have to defeat any other pokémon that Gumshoos called into battle.
Get a Z-Crystal
After you win, the Trial of Ilima is complete, and you can take the Z-Crystal, Normalium Z. If a pokémon that knows Normal attacks holds the Normalium Z, that pokémon can use more powerful versions of those Normal attacks in battle.
Now that you have a Z-Crystal, the Poké Marts will add Great Balls and Super Potions to their selection.
Ilima gives you 10 Great Balls. You can now catch pokémon in Verdant Cavern and you might encounter pokémon as you walk around.
Then Ilima heals your pokémon.
You can't reach the TM that you see in the back of this room right now, so go downward back to the first room of Verdant Cavern.
Inside, you will meet members of the Ultra Recon Squad.
When you go past dens in this cave, you might get attacked by pokémon from the dens and encounter wild pokémon as you walk around.
When you leave the cave, Ilima opens the barrier to Route 3 for you, and tells you to let Kahuna Hala know that you completed the trial. Then Professor Kukui arrives and demonstrates how to use Z-Powers. You don't need to press any buttons during the demonstration. You can only use one Z-Power per battle.
Then Professor Kukui asks you to look for Lillie in Route 3, because he can't find her. Go up the path to reach Route 3.