Reddit's pretty terrible for discussion, but if you're super casual and just want the most basic discussions, you can try your luck there.
Bulbagarden's decent, but you have a lot of idiots who just talk out of their ass and have no idea what's going on, or super nerdy elitists who care more about winning fights than talking. There's little in-between, but when you find that good spot, it's really good.
Serebii's a lot like Bulba, except there's less elitism and more stupidity. I guess that makes it more fun.
As for roleplays, where are a few cites and Tumblr groups for it. The problem is that, from what I see, all RPs slow down or outright die off after a while. Even in a popular franchise as Pokemon, it's hard to find roleplays outside of ERPing.
YouTube is great, because you're almost guaranteed to be the most intelligent person in a comment section, and your taste will always be better than everyone else's.
There are Twitter and Tumblr fan groups. On the plus side, they're small and cozy, and somewhat active. The downside is that they're on Tumblr and Twitter, and they attract the stereotypical ilk.
Finally, you could stick to /vp/. At least it's better than YouTube comment sections.
