I thought this thread was about matchups, not characters
There are already 1000 threads about which character is easiest to play, we should just talk about matchups that are different in high level play and how they change as they get better, it'd be far more interesting.
That said, the matchups I believe are different in high level play than mid level play are Marth vs. Sheik, Falcon vs. everyone, and Top tiers vs. low tiers.
At low-mid level, Marth vs. Sheik is 30:70, and it gradually improves till high level where it's almost even (like 45:55). If the Marth player does not know how to play safe, he will get *****. Sheik will shield grab Marth all day, and without good DI, he will take so much damage from each grab with braindead easy combos that mid level Sheik can perform. This is assuming mid-level Marth won't jump out of the chaingrab, wont SDI the ftilts, and wont know when to interrupt with a fair. Both will be clueless as to how to edgeguard with cancels each other out. But once Marth plays a little safer, he gets grabbed less and when he does get grabbed, he doesn't take very much damage. Marth's uthrow seems more dangerous than Sheik's dthrow at low percentages, and he can play a spacing/DD game that he can win as long he doesn't make a mistake. Both edgeguards get crazy strong. As a mid level Marth player this is my favorite matchup and it's the only one I feel I've completely figured out... but damn did it feel like a steep uphill battle at first.
Falcon's matchups really seem to change at higher level. The main reason is the Falcon's ability to combo, and the ability to DI out of death combos where his death combos are very difficult to escape. Before the Falcon gets good though, he fights an uphill battle against everyone, even low tiers. Every mid level player can edgeguard and combo a Falcon. It's too easy. Falcon will not be able to do either until later, at least not without killing himself.
Low tiers seem to do just fine against mid level players, but the matchups get worse and worse as players get better. In a tournament, low tier players usually have the advantage against mid level players because they will almost certainly not know the matchup, but later on they will find out exactly why their character is low tier.
