|Altaria||Dragon/Flying||Any Grass||5%, 15% (Dark Grass)|
|Mienfoo||Fighting||Any Grass||20%, 30% (Dark Grass)|
|Buizel||Water||Surfing||30%, 60% (Rippling)|
|Red Basculin||Water||Surfing/Fishing||70%, 30% (RIppling, Fishing)|
|Blue Basculin||Water||Surfing/Fishing||70%, 30% (RIppling, Fishing)|
|Goldeen||Water||Fishing||70%, 60% (Rippling)|
Continue down the beach, past the Socialite and past the steps leading south, right to the end. You'll see an item there. Pick it up and you'll find that it's a Big Pearl . Move back to the Socialite and challenge her!
Trainer Battle: Socialite
Now move up the steps leading south. There's a Gentleman there who'll take you on.
Trainer Battle: Gentleman
Continue south down onto the bridge and move over it. There's a Battle Girl here. Battle her (See what we did there?).
Trainer Battle: Battle Girl
Simply follow the path over the next bridge to the Ace Trainer and take her on. This battle's a Triple Battle, so adjust your party accordingly before you head in.
Triple Battle: Ace Trainer
Go south-west over yet another bridge then head up the stairs taking you west. Instead of continuing up the second set of stairs, head north into the Dark Grass. You'll see an item to your east. Grab it to find that it's a Max Potion .
Now head west and speak with the Fisherman to initiate a battle. Meybeh time to serve up a dish of pwnage?
Trainer Battle: Fisherman
Now jump on your Pokemon and Surf over the steam to the north-east. In the Tall Grass there you'll find a Backpacker looking for someone to get beaten up by.
Trainer Battle: Backpacker
Once he's been dealt with, head over the water to his north. At the end you'll find a small amount of land with an item on it. Grab it. It's a Heart Scale ! Now, backtrack all the way to the Fisherman, then head back out of the Tall Grass. Head up the small set of stairs taking you west, to the male Ace Trainer there. Rotation battle time!
Rotation Battle: Ace Trainer
If move west up the next set of stairs, you'll find a gatehouse that leads gate to Black City (if you're playing Black 2) or White Forest (if you're playing White 2). However, you won't be able to pass through until you've beaten the Pokemon League as a bunch of random weirdos are blocking the way.
Man, they're not even trying to give us a plausible explanation anymore... If you have beaten the Pokemon League, feel skip ahead to the appropriate section. If not, head back to where you are in the game. If you haven't gone north from Undella City yet, that's the place to start!