There's a room under the bridge here you can enter, where a girl is waiting during the day- she shouts at you that she's 'practicing' and shoves you out of the room.  If you then head up onto the bridge and talk to the woman standing over that area, you can tell her about the girl practicing her singing, and recieve a set of five Sitrus Berries, useful for mid-battle healing of your pokemon (preferably as a hold item).

Head North under the bridge to pick up a Blue Shard behind the basketball court, and Surf into the stream to grab a Big Pearl from the little island with the grass on it.

Return South while still on the river and you can pick up a Heart Scale from the rocks around the bridge pillar, and fight a fisherman.

Battle: Fisherman Dean (1344 Poke)
Opponent: Basculin Lv 42

With that, you're done in Village Bridge for now, so move on to the West through the city gate.  This puts you on Route 11, which is chock full of things.  While you can’t access all of the area just yet, the grass here holds a wealth of pokemon old and new.  Golduck, Marill, Zangoose, and Seviper make appearances here, as does Amoongus, the evolved form of Foongus.  Also in the grass are Shelmet (Rarer in White 2), Karrablast (Rarer in Black 2), and Gligar.

Shelmet is a slow, tough pure-Bug type that evolves when traded with a Karrablast into the ludicrously swift Special Attacker, Accelgor.  Accelgor is a quirky reversal of Ninjask, putting together insane speed with somewhat nice Special Attack and sadly rather frail defenses.  While it trades in Ninjask’s constant acceleration for either healing status immediately in the rain or preventing its held item from being stolen, it has the advantage of being one of the rare pure-Bug pokemon and thus only having three weaknesses, none of them double.  Its movepool is wide but rather shallow, as most of the tricks and special effects it gains access to are by and large useless for it, but it has an interesting array of attacks in enough different types to somewhat mitigate that.  Shelmet’s thieving partner, Karrablast, is a physical attacker that steals Shelmet’s shell when traded with it, to become the Bug/Steel knight, Escavalier.  While Escavalier has all the speed of a crippled Torkoal, its defenses are high and its Attack monstrous, combining well with its having weakness only to Fire attacks.  Very few of Escavalier’s naturally-learned attacks exceed 100 power, as the pokemon prefers to lean on its defenses to keep it in the battle for another round (and let it make use of Giga Impact).  In fact, TMs and the Move Tutor still don’t give it access to higher-powered attacks ever, but they do give it access to a wider array of side-effects and special-effect attacks- and putting its Attack power and Swords Dance (which it learns naturally) together make it horribly dangerous until it’s touched by a few sparks.