Hmm, I don't know.
Personally, I'm a huge fan of this Assist Trophy idea. Assist Trophy opinions seem to either be completely optimistic or completely pessismistic. I myself am the optimistic thinking, "Well, the character had the option of never appearing in the game because he didn't make the roster, or being an Assist."
I'd rather have an Assist than nothing... even if Wolf O' Donnell is an Assist >.>
Now then, someone made a valid point earlier. Sakurai did say that the Nintendog was an Assist Trophy, so this could mean that Assist Trophies have been around from the start. However, I still doubt that ended up effected the actual roster, as many have said.
Sakurai also mentioned that some Assists would be very unfamilar to but a few gamers. Let's think outside the box. No, I don't mean that one random enemy you see once in the game that you killed in two seconds in, say, Gotcha Force *shrug*. Oh wow, that just hit me... NEO G RED AND RAY 01 FOR ASSIST TROPHIES! FUUUUCK YES!
Sorry. So what "obscure" Assists do you think will appear?
On a side note, it seems like this game had everything from the very first trailer we saw >.>
I think God just handed Sakurai SSBB and was like, "Alright, look man. Keep this on the down low and release information to them slowly. Can't have them getting any ideas."