Here's my Super Smash Heroes series where I draw the all the Smash Fighters as Marvel and DC! Here's Charizard as Hawkman!
For those playing at home, there are too many Hawkmen with too disparate origin stories and DC keeps trying to make them all exist at once no matter how little sense it makes. This is completely different from how Charizard keeps getting every new toy that comes into existence.
This is a great choice.
And while we're waiting for Diddy, here are my guesses for the next four after that monkey. For Lucas, seeing how he's known for his psychic powers, he would very likely be some DC character with psychic powers, like Martian Manhunter for instance. For Sonic, I've mentioned it before and I'll mention it again: Quicksilver. I would be shocked if he was anyone else. For King Dedede, Oswald Cobblepot AKA the Penguin. As for Olimar, well, your Young Link x Hawkeye pic had a Pikmin on Young Link's arrow, very likely teasing that Olimar is going to be Ant-Man.
I agree with you on Sonic, Dedede, and Olimar. On the other hand, Diddy should probably be a character associated with the Hulk.
As for alts, I’m pretty sure Bryx said he/she (don’t recall his/her gender offhand) wasn’t going to be doing alts. Shame really—maybe we could come up with ideas for those and/or the Assist Trophies...