are you just gonna ignore this post
i think the thing about a question like that is it's difficult to answer without a copout like "choose sheik or projectile character lol"
if you ask "how can you counter them" it's similarly difficult to answer because there's going to be a bajillilon exchanges between the players per stock which varies in percentage, location, and even what stage. a classic tip is "mixup your options and space better" since that's all encompassing and vague enough to not help much at all.
that being said, i'd recommend watching videos of high level players (like ally with mario or 6WX with sonic) to examine the exchanges that go on in their matches.