obtain national pokedex
u have to get complete the national poke-dex by raymond
Catch all the pokemon in the region. Get the national pokedex
You to have a tag battle with them with your rival as your partner.
in the fight area
you have to beat the game and have national pokedex and the people blocking your way to go out of fight area will be gone and once you go up there will be a fisher man talk to him and he will give you a super rod :)
You need to get the national dex, so you have to see all the sinnoh pokémon, then go to professer Rowan and he will give you the national dex as reward.
In the fight area you can access the Battle Frontier, and route 225 to Survival area, or route 230 to Resort area.
you just battle at ..........BAAATTLLLEEE TOOOWWEEERR!
Get the super rod from the bloke in the Fight area below route 225. (You'll need the national dex so the people will move that are blocking the way). Use it by the water in route 230. It should be there.
you catch banette at the fight area, resort area or survival area
A fisherman at the fight area gives it to you.
All you got to do is go to fight area and go to the right where those guys were at then use hm surf and there you are!I hope that helped!