Here is my new, more reasonable list that fills the needs of the audience, rather than myself, as well as being easy on the devs:
1. Ridley - possibly the no. 1 most-wanted character, as we all know Metroid needs another rep, some well done PSA's, model in game but needs shrinking
2. Isaac - assist model in-game, wildly popular
3. Waluigi - already very-well created PSA, has the assist trophy model, well-known
4. Pichu - easy to make, and with my request of young link below, every fighter from every installment would be included in Project M.
5. Not sure; could be for Young Link (see below), or the ganon/black shadow swap, or keep original ganon and fill this slot with ganon 2.0
Bonus - I would like to see Young Link replace Melee Link as Link's alternate, or at the very least fill up his final alternate slot. That way we would have every character from every installment.
To solve the lack of the Pokemon trainer, they could put him in the background for every Pokemon but Mewtwo, cause he's bad*ss. Or they could put him in the background of just the Pokemon stages.