Now that we have a matchmaking system, I think it opens up some doors to a lot of different rule sets/battle styles to become more standardized, but I particularly like the idea of rental Pokemon.
Of course, they'd have be random rental Pokemon. Being able to create your own to battle with would be far too distracting for an MMO. And yeah, it'd definitely take a fair amount of time to come up with random movesets for every single Pokemon (like Stadium), especially while trying to keep it balanced, so it's definitely low priority. Still, it's something I'd love to see implemented somewhere down the track.
This would also give players the opportunity to use legendaries without actually owning them.
Thoughts?