I've said it before and I'll say it again, Sinnoh is the best region as far as the anime goes. Evolutions, rivals everywhere, a lot of captures, and a GREAT supporting cast. And the first in-game rival that's more than just a cameo since Blue's influence on Gary Oak.
Rival Jun/Barry is just great in so many ways. His ideology for Shinji/Paul is similar to how he ideolizes Crasher Wake in Pokemon Platinum.
I don't want to spoiler anything for you, Bowser Ex, since I watch the Japanese episodes. But you are in for a treat when you "catch" up.
The only bad thing is the English opening theme. I've actually liked all of the English themes so far (Diamond/Pearl, We Will be Heroes, Battle Cry! Stand Up), but this latest one just flat out sucks.