Wow, some intense reading there. All in all, i liked the moveset, although there were a few things i had some points on...
In your alternate Down special you pointed out about the chances of picking up one thing or another. But your chances don't quite make sense. On one, you said there would be an 8o percent chance, and on another, 30 percent. It doesn't add up, but i might have just missed something.
The other thing was pretty much that his moveset is slightly overpowered, but since he has such short range with the rest of his attacks it probably wouldn't be a problem.
Otherwise it was a fun and interesting read, and it's a tribute to his importance in the mario series, taking moves from anywhere and everywhere. I'd say people would get a lot of fun out of his moves and his taunts(which i noticed came a lot from mario kart((i've only ever played the first one and 64)) which was fun to see).
On a side note, his aerial side was a head bash which you said was a meteor move. It's interesting but me and my brother have always called those moves golf moves: You see, back when we used to play 64 a lot, i used to be ness(as is my 64 character postbit shown under the avatar) and one day i used his down aerial on kirby in saffron city(between the two towers on the right). Me and my brother laughed about this for a while before we labelled the act kirby golfing(i'm sure you can see the reason why). We started to do this with other players and whenever we do it we just use the name of the char e.g. "Mwahahaha! I just played Pit golf!", or "Hehee! I just played mario golf!(no pun intended
)", so nowadays we call the act golfing and any act we do that does the effect(ness' down aerial still, C. Falcon/Ganondorf down aerial etc etc.) golfing.