Honestly, I wish project m made sonic's recolors (not alt costumes, the recolors they included in game) of sonic like this:
It would make a lot of people happy, I think they are more fitting, and personally, I prefer them to the P:M recolors. (Though, the P:M recolors are infinitely better than vbrawls recolors.)
There's not much more they could do to improve these recolors,
Really, the shoes are good as is, but there is room for improvement, like black and green shoes on scrouge. There are plenty of imports and other hacks of of the actual character that the shoes could be taken from (perfect shadow) to make the shoes a little better.
In addition, they could have arm bands that represented the character better (gold ring on shadow and silver, and a green band on knuckles) that could also be taken from characters.
Finally, sonic could have the back of his quills highlighted red (but it's good as is).
These are NOT suggestions for sonic alts. It is merely a suggestion of better recolors for sonic (to ovetake the previous recolors)
Diddy wears Dixie's outfit, and Peach wears Daisys, and Luigi wears Waluigi's, and Captain Falcon wears Blood Falcon. I believe these recolors follow the rules, and falls within the guidelines. It would be a nice reference, and the very verbal sonic fanbase would be happy.
^_^
Scourge, or however you spell his McDucking name, is from an official comic book that are based on the games.