Essentially, the titles listed there are what those composers would probably use as the highlights of their resume.
Saying "the guy who did the music for Kingdom Hearts" makes people take notice. Just listing his name, not so much.
The example titles mean nothing but to assure you of the quality of their work.
Now, that's not to say some games listed won't have a character or level in Brawl. But using the list as a deciding factor is pretty irrational. Later on we may see someone, then point back to the list, saying "oh, yeah, now that guy's involvement makes sense". But not the other way around, pointing at things that might nto exist due to a name.
For example, many comic books have guest artists. I read a comic recently that had artists from all over the place doing it, each one a seperate page in the story. I didn't look at the artist from Spiderman and think "he's working on this comic, that means Spiderman will be in it". Because that's not how things work. Spiderman could have been in it, I suppose, but it was somewhat unlikely because the comic was a Superman/Batman one.
This applies now. Just switch the word 'comic' with 'game' and 'Superman/Batman' with 'Smash Bros', and 'Spiderman' with 'Crono' or 'NiGHTS' or any number of characters, and my long-winded post's purpose becomes clear.
To summarize:
That list is a list of notable things people did. Those people are involved. The things they did could or could not be involved. But this list does not mean they are.
