I personally think sonic can be a MK counter if played correctly. Fsmashing his mach tornado at a certain spot will ether override the move and hit them or cancel both moves. Leaving a chance to ether dash attack, or fair, or nair, or grab. Also you can try and dair above MK's mach tornado and cut through it or up smash and completely cancel both moves. Another thing you can do is try and footstool MK's when they try to fly back to the stage keep footstooling them until they ether A die or B until you can't footstool anymore. I have done this to many MK's before sadly i don't have any vids to show of this. But Mk has flaws that alot of us sonic's ether don't see or don't use. Mk requires a completely different approach thus testing Other characters to create new tactic. I will continue to find weak points in MK and bring you guys more about MK's moves and how to beat him soon.
You give interesting points, but unfortunately they're sort of avoidable.
- If both moves get cancelled, then the tornado was:
1) grounded
2) used as an approach
instead of a punisher move.
If you can hit MK's tornado with D-air, he's probably still not using it as a punisher move.
- MK also can double jump quicker (and 'safe' from footstools) if he uses U-air as he jumps.
IMHO, if you want to have less of a harder time against MK, you need better habits as a player - learning to and being able to punish ASAP out of shield (like, if MK F-airs your shield, do a SH F-air and hit him out of it - or if MK tornados your shield, then release and chase the tornado as soon as he lets up). Those aren't the only moves that you can pull this off on. Sonic's speed makes it easy for almost any character to misspace, and MK's moves are pretty much all punishable as long as he misspaces.
MK's quick and high-priority moves make it easy for him to play aggressive, but more importantly, it makes him a tougher defense to break if he's playing campy and:
1) Knows how to fight Sonic (knows about shield cancels, common approaches
2) You don't adapt to him.