After defeating Wulfric and earning the Icicle Badge, go through Dernière Way to reach Victory Road.
To find all of the items in the route, bring a pokémon that knows Cut, Strength, and Surf.
In the grass and flowers, you might encounter Scyther, Ursaring, Spinda, Altaria, and Floatzel. You might also encounter hordes of Scyther, Spinda, and Swablu.
While surfing, you might encounter Lombre or Floatzel.
When fishing with the Old Rod, you will encounter Poliwag. With the Good Rod, you might encounter Poliwhirl, Dratini, or Basculin. With the Super Rod, you might encounter Poliwhirl, Dragonair, or Basculin.
Battle and Catch
After you go west across the bridge, you find Ace Trainer Mireille standing near the flowers. She has a level 55 Sableye and a level 56 Crustle.
East of the red flowers, you can use Surf in the water. Go north in the water to find an Insect Plate. Surf south to go back to the red flowers.
Go north from Ace Trainer Mireille to find Ace Duo Elina & Sean. They have a level 57 Wailord and a level 57 Vileplume.
Turn on your Dowsing Machine to find a hidden Guard Spec. on the rock east of the Ace Duo.
East of that rock, there is a boulder that can be pushed with Strength. Push it east three times, then push it west once, then north until it falls into the hole.
North of where you pushed the boulder, you find Veteran Louis, who has a level 55 Hippowdon and a level 57 Aurorus.
Near Veteran Louis, you find the Move Tutor House. The Move Tutor can teach Draco Meteor to Dragon-type pokémon. There is no cost to learn the move, but the pokémon needs to have high friendship before the Tutor will teach it the move.
Outside of the Move Tutor's house, turn on the Dowsing Machine to find a hidden Pearl String in the purple flowers.
Surf in the water west of here and go northwest to find a Repeat Ball.
Use Cut west of there to reach a Figy Berry tree.
Now return to where the Ace Duo are standing. There are some stairs to the left of them. Go west up those stairs. If you keep going west, you'll reach Victory Road. However, there are some items that you can get if you go south down the ramp.
In the southwest area of Route 21, there is a puzzle where you have to push multiple boulders using Strength. You will also have to cut some prickly trees with Cut. You can find some useful items in this area.
First, go west. You'll find Ace Trainer Evan running around the red flowers. He has a level 58 Chandelure.
Use Cut on the tree near Ace Trainer Evan. Go south past where the tree was, then push the leftmost block as far left as it will go.
Go east and push the other rock to the left until it hits the first rock that you pushed. Now push the lower rock down until it falls into the hole.
Go back to where the tree was, then go west along the narrow northern path so that you reach the first boulder that you pushed. Use the Dowsing Machine here to find a hidden PP Up on the rock.
Push the boulder east until it falls into the hole.
Go south and push this rock into the hole. Then go back to where Ace Trainer Evan is running around. Go west up the ramp, go west past the red flowers, cut the tree that is in the way, and follow the path along the ledge. You will encounter Veteran Trisha, who has a level 59 Tyrantrum.
Pick up the Elixir that is east of Veteran Trisha.
Go down the ramp and push the boulder east into the hole.
Surf east until you reach an area to the south. Pick up the Rare Candy that is in that area.
Get in the water and Surf west until you see a prickly tree to the north. Get out of the water and use Cut on that tree.
Get back in the water and Surf west. When you get back onto land, walk north over the boulder in the hole, then go east.
Push this boulder east until it falls into the hole, then go east and north. Push the boulder up three times, then east until it falls into the hole. Walk across it and go south to get TM22 Solar Beam.
You have found everything in this route, so go northwest to reach the gatehouse to Victory Road.