I'm glad to hear that you can customize trainers. I hope we get to choose the color of our bags as well.
As for customizing Pokemon, you could only do that at the musical and nowhere else (in that case dressing them up with props) I like the idea of showing visible items on Pokemon, however their are a couple of problems which hinder their chances of this happening. Firstly, the size of each and every Pokemon are different, and GF would have to modify the size of something like a Choice Band, otherwise it would be too small by the time a Pokemon evolves. Secondly, it trolls Pokemon that have the Frisk ability, because it means that Frisk won't be useful anymore.
As for Contests, I would like the see the Gen IV contest make a return this year, rather than a stupid musical. It would be interesting to see which moves will be categorized contest-wise as well as type-wise.