The floaty thing is big to me, brawl changed the whole tempo of the game with slower fall speeds, easier ledge grabs, slower attacks, and also the fact that KOs happen more at 200% or more rather than 100%, though I know many casual players insist that it should be this way to be easy, maybe a hardcore setting with faster tempo, no items, etc. is due
I'd also like to see some corrections to characters to be more potent, an example being jiggly puff, a direct hit of rest is supposed to be tough to pull off but powerful and exciting, melee did this well but it was completely pointless in brawl
With clones, tough to say, falco has pretty much proved his residency here but I don't care for clones too much
The new costumes thing is great, but I disagree with your "store idea" as I think that would be a waste of time, just make costumes and color changes like warios in brawl
Anyway I would like to see them fix some shortcomings we saw in melee, floating down to catch a ledge backwards at 300% playing a light character is ******** IMO, sorry for my harshness