if sonic does return i hope sakurai treats him like how he did megaman. sonic in brawl for all the things they did right for him they still made him feel half full. the fact he was given two variations of his spin attacks speaks volumes about that.
Now i know sonic's moveset works well in brawl i just feel it can be improved upon to better reflect sonic's essence as a character, especially if he had moves based around games he's been in rather than a subsidiary fighting series from sega.
neutral B: homing attack- basically the same as it is now except a tad less startup lag and allowing you to react sooner on hit to better the overall flow of the move.
side b: that new spin kick from lost world on 3DS- that move could be used as A) a projectile based special for sonic or B) something like how sonic wind works as the moves aesthetics bare a striking resemblance.(heres a picture incase you dont know what move i'm referring to
http://operationrainfall.com/wp-content/uploads/2013/06/28078W1T_12.jpg )or they could use the light dash/boost and make it function like fox/falco's illusion except no freefall
up b: spring- same as before but he should'nt be able to be grabbed out of it and penalized with not regaining it and the falling animation could be how sonic falls in most of his modern games instead of spinning like he does.
down b would be his spin charge/spin dash and work the same as in brawl.
fair or dair could become the sonic eagle from sonic battle, his uair could be an aerial variant of his sonic upper from sonic battle his jab combo could draw from there as well.
his walking animation imo should look as close to as possible to the ones from the games when he's building up speed and he should'nt need to be so hunched over when he's running with his super peel out, they could also make his animation when he gets hit to match how he looks when he gets hit in the games, they slightly draw from it but still doesn't quite look like it. i would say they could make sonic looks his rings and when he dies you see rings flying or whe he gets hit rings come out. the fact that megaman is getting special treatment in nearly every aspect i find more of a nod towards the fact that sakurai rushed sonic into brawl without completely capturing sonic as a character.
i mean i'll be satisfied and grateful if sonic returns but i still will feel like sakurai hasn't done sonic justice unless he takes the time to really make him feel like sonic, not a what if sonic was from virtua fighter and thrown into smash version.