EDIT: Time for me to make my list. I'll steal Paper Maribo's template and focus on the characters I know.
Advantage 60:40 or above
Advantage 55:45
Even
Disadvantage 55:45
Disadvantage 60:40 or more
Incomplete list, due to incomplete knowledge. Marth/Lucina has a surprisingly decent matchup against us IMO. Without a projectile, you'd think we'd outzone them, but the high walking speed, aerial mobility and 10-frame FSmashes are quite threatening. I wouldn't be comfortable giving us anymore than a 55:45 advantage.
The only characters with a truly awful matchup are Luigi, Rob, Capt. Falcon and Ike. These characters seem to have large-blindspots in spacing that PacMan takes advantage of. Gannondorf has this blindspot too, but his quick KOs and huge-mass are enough to make the matchup closer to even.
Donkey Kong's size is deceptive. He moves extremely fast and I don't really consider him a heavy. Strong aerials (invincibility on up-B) and super-armor options on the ground make him a threat in my eyes. His range is huge, got the speed to do all the footsies and KOs rather quickly.
Robin is a very interesting matchup. Despite having very poor mobility, Robin's footsie game is amongst the best in the game. We edge out an even matchup IMO due to our superior mobility, but every time we go in on Robin is a
major risk. We control the flow of the match, but Robin basically can react to everything we throw at him.
PacMan vs Robin has to be one of the most
interesting matchups we have. Both characters are toolbox characters: Robin's four different thunder charges provide him with many excellent options. His poor mobility is somewhat mitigated by careful BReversal plays and huge zones where he commands a footsie advantage.