For this Route it should be pretty straightforward. For getting to the berry patch and some of the items you will need Cut, Surf, and Rock Climb. Fortunately none of the HM moves are necessary for progressing through this route to reach the Survival Area. Notably around the only house in this area is the Lax Incense, the only Incense that cannot be collected during the main game which you will need Cut to get to. Other items on this route include evolution items, though pretty much all you them have been found earlier in the game and all you can do is get extra copies of them.
The house on the west side of the Survival Area is the Battleground, a special facility which you can't access until you complete your upcoming mission to Stark Mountain. If you use the ledges near the west side or the small path on the east, you'll reach the house located in the south of town. Inside is a man that will give you TM42 (Facade).
The house on the cliff has the final Move Tutor in the game. To access it go east to Route 226 and use the first Rock Climb ledge you see to go up there. Like the previous Tutors you will need colored shards to be able to teach your Pokémon moves they are compatible with.
For this route you will need Rock Climb and Surf. For the first part go to the Rock Climb ledge to the far right climb up it. The trick to getting to the berry patch and the items is by carefully observing which Rock Climb ledge goes to where. To make it easy go to the ledge to the right that leads down. Then go to the nearby ledge that leads up. Now go to the ledge near the two trainers that leads down (though go the ledge after facing those trainers to find TM53 (Energy Ball), a useful move). Now you can get to the second part where Surf is needed.
In the second area you will find a house belonging to a man called the Meister who is German in origin. He will perform an upgrade that will store Pokédex entries from Pokémon games from other countries. He will also trade you a Magikarp from Germany in exchange for Finneon. To the east of his house is a grassland area that leads to Route 227 and Route 228. Head for the north exit that leads to Route 227 first.
As you notice when you arrive here is volcanic ash in the air, as you are close to Stark Mountain, which is an active volcano. Carefully jump over the two bike ledges with the bike and after the second ledge jump over the regular ledge once, but careful not to jump over the second one to a avoid backtracking. After that you will see Barry and Wake, and after Wake acknowledges your growing strength, Barry annoys Wake again by calling him master despite not being made Wake's apprentice and Barry pleads that he needs him to enter the Battlefield club. Wake will point out how prepared your team must be for dealing with Stark Mountain before he leaves with Barry right behind him.
The lady in the nearby house will let your team rest when you talk to her. Follow the path and you'll encounter Buck again. He asks you to go up to Stark Mountain to patrol it and guard the Magma Stone which keeps a certain Pokémon asleep and that a group of vandals that dress like spacemen have been plaguing the area lately. Buck mentions he can't go as his Pokémon are low on HP. Continue following the path and you will reach Stark Mountain.