Gonna step in and give my two cents here.
Judging by the work that has been done for Project M, Waluigi had the potential to be a very unique character. Does this mean I wanted him in? No. Did I absolutely hate him and wanted to kill anyone that supported him? No. I was indifferent. If he got in, I wouldn't cry and throw a fit over it, and I wouldn't do that if he DIDN'T get in either.
Now I'm going to get on people's nerves even more by saying I personally don't know about the Wii Fit Trainer. Mega Man was an obvious pick, the Villager is an interesting choice, Rosalina is... eh, I'm indifferent. But the Trainer comes way out of left field, and while the moveset and all looks special, that slot could have gone to a more deserving character. Do I mean Waluigi? No.
Also, a thing people should take into account is that a lot of the characters you're suggesting are pretty unrealistic. I'm not talking about Ridley, but more about choices like Kystal and a bunch of Fire Emblem characters, stuff like that. They're not 'big' enough and possibly not popular enough. Keep in mind why Sakurai refused to make Waluigi a roster character: probably due to the lack of strong presence.
But I'm not hating on anyone just because they want a character in. I don't understand why Waluigi was such a feared character to be a part of the roster considering he IS an important figure in the Mario party-themed games and such, and with Wario being his partner, I can see why he would fit.
tl;dr Stop crying, it's kinda pathetic.