In the Northwest corner of the city is the Gym, but you don't want to head in just yet.  Instead go South from the Gym to the next building you can enter, where you can hear a little about musicals (and the top floor has a couple of guys at a table together who have some interesting thoughts about Team Plasma and their ideals two years ago).

Loop around and head up the road to the left of the Pokemon center (by the musician) and you can find Drayden's house.  A football player who is, for some reason, in the upstairs of the building will give you a Float Stone, which is a very odd hold item.  It cuts the weight of the pokemon holding it in half, which does nothing at all most of the time.  In fact, the only things it alters are the moves Low Kick and Grass Knot (which will deal less damage to the pokemon with the Float Stone), and Heavy Metal (which will deal less damage coming from the pokemon with the Float Stone).

The woman across the table has a Ring Target.  This strange item makes the pokemon holding it able to be hit by any move, even moves it is normally immune to.  This item is essentially useless outside of Double and Triple battles, since enabling your opponent to hit you just isn't helpful.  Used properly in a team battle, though, it can be hugely useful with the right moves and pokemon selected.  Be very careful with it regardless.

With Drayden's house cleaned out, all that's left in Opelucid is the Gym, but you should really take Iris' advice and head West first, to Route 9.

The grass in Route 9 has some nice opportunities in it.  While the Liepard you find here remain disappointing as ever (thanks to an even more severe case of Floatzel Syndrome than even Floatzel has), Minccino is here, as is your cartridge’s slow Psychic type- Gothorita for Black 2 and Duosion for White 2.  Garbodor can be found here, a hideous but effective Poison type with the usual capabilities of Poison types- high defenses and good HP offset by poor Speed and middling attack stats, combined with a surprisingly wide attack pool and lots of special effects.  In a similar vein is the original pollution pokemon’s evolved form, Muk.  The really interesting inclusion here is Pawniard, the Sharp Blade pokemon- a Dark/Steel type of remarkable capability.  Pawniard evolves into the highly hazardous Bisharp at the staggering level of 52, which Bisharp at first doesn’t seem to earn- its speed is mediocre, its HP is on the poor side, its Special Defense is a touch poor, and while it has nice Defense and very strong Attack, none of that really matches up with a pokemon caught this late and evolving even later.  The real power of Bisharp is in one of its abilities and its movepool.  Wild Bisharp may have the Inner Focus ability, a handy little trait that prevents the pokemon from ever flinching unless interrupted while using Focus Punch.  This ability is alright, but hardly impressive.  Much more useful is Defiant, which boosts the pokemon’s Attack stat two stages every time an enemy lowers any of its stats.  This makes Metal Sound, Screech, and other similar moves horrible liabilites, as well as overcountering attempts to lower Bisharp’s Attack stat.  More importantly, Bisharp has access to a lot of high powered physical attacks and naturally learns Swords Dance (if a bit late), letting it wreck anything that doesn’t take it out quickly.  The chess piece has a lot of trouble with Fighting types, but as those rarely have access to any way to prevent it switching out and Rock Polish is also a thing, Bisharp can still present a hazard to such pokemon (particularly if equipped with Aerial Ace).