Diddy - 6:4 Diddy (I think it could be as bad as 7:3 in favor of Diddy)
DK - 8:2 Dedede (Why? I think its 5:5 or 6:4 in DDD's favor without using infinites)
Fox - 5:5 Even (I think its 6:4 Fox favor)
Shiek - 5:5 even (I believe its 6:4 Sheik's favor)
Squirtle - 6:4 Dedede (I think its the other way around, Squirtle having the advantage)
Again these are just my opinions from matches I've had in the past.
Other then that your list looks great.
I meant to put 7:3 in DDD's favor for the DK matchup. Infinites is really what puts him at the disadvantage obviously. You're right without infinites though, its a good matchup I would still say 6:4 in DDD's favor without the infinite.
Obviously were still gonna have slightly different opinions based off the people we play but it's good that we agree on most things.
You're probably right about Diddy however it is as bad as 7:3 or at least 65:35.
I play 1 really good PT player and for some reason squirtle gives me the least amount of trouble out of the 3. Its pretty easy to keep him away from you with Ftilts and Up tilt and DDD's bair beats out his. Its easy to shieldgrab his attacks if he does get in close, and he's semi-easy to gimp which is why I felt it was in DDD's favor.
Fox and shiek can obviously be argued either way too,
The main thing for me is that waddle dees/doos on the stage stop their projectiles, so you sort of can outspam them and force them to approach and just play them defensively although when they do get hits they can combo ddd to hell.