Sonic's f-smash and bair both have ridiculous disjointedness (as well as range), and are safe on block. And he has better priority than half of the cast. I really wish people would get over this "Sonic has no range/priority/kill moves" stereotype that has been proven wrong months ago.
You can literally just pivot f-smash characters
through their attacks, and you say Sonic has bad kill moves? You see Metaknight do a retreating fair? Pivot f-smash. Tornado, run away and dash cancel f-smash (through the ****ing tornado). Fox is above you about to dair? Pivot and start charging an f-smash.
In fact, you might as well use pivot f-smash to rack damage while you're at it (thank you no stale moves) and still kill with it since it's just that easy to land f-smash.
Sonic has no problems killing.
Maybe at high percentages. At low percentages you can chain fairs together, link uairs after that, and then use your side B->jump to chase their DI for one or two more uairs. Then you just set up a juggle trap (since Sonic's uair outranges every dair in the game except Ike and DDD)
How about safe kill moves, better edgeguarding, dash dance mixups, dash cancel mixups, faster damage racking, and actual kill setups (in addition to tech chasing and shfflcombos like you've said).
Sonic is easily top tier material.
I don't think he needs to be nerfed at all (totally biased opinion
), but really every single change that has been made has helped Sonic tremendously (Except upgrav,which my friends and I don't use anyway).
/Sonic is top tier rant.