Who do you collect, and what merch is there for them?
As for me, I collect Jirarudan (aah, back when they actually released movie stuff that wasn't entirely about the pokemon of the day, eh?) and Team Galactic. Also obscure Rockets but my collection of them is pretty much limited to a Domino settei. TG stuff, not counting the DPA and Pokemon Special manga series, there's cards, the Cyrus DSi cover, the anime dvd (which I don't have), and the TCG poster (which I...also don't have), and a metric buttload of settei.
I really wish they made Evil Team shirts. It would be awesome. I'd wear mine all the time, only taking it off to change it to another one. I'd wear them to bed. I'd wear them to the store. I'd wear them to the friggin' symphony they'd be that awesome.