A bit of thread necromancy, but I was wondering the same thing and while "if a mod has Persona support it will tell you on the page" is true, that kinda requires reading every mod page?
So in the interest of giving future readers a place to start, I just loaded up all of my character mods in Persona to see which ones popped up, and presumably (I remember for a few) have Persona support on their mod page. Note that this list is nowhere near exhaustive, it's mostly just among things I already had installed for regular SRB2 or from previous times I got into SRB2P. Also, apparently Gamebanana is actually the usual place for SRB2P specific mods? Lurking the discord a bit has a lot of gamebanana, and apparently even the Bionis Fields V2 mod from the Mod Direct is actually out but it's over there.
Persona Characters I found on the MB:
RChars, that's Metal Knuckles and Tails Doll
Whisper (I've used her, actually, she's good)
Surge (ditto)
Cacee The Cactus
Mario and Luigi, SMS Alfredo's version.
Silverhorn
Werehog
Espio, standalone but not the Chaotix mod, whose title screen seems to break Persona
Blossom and Flimp
Sonki
Pointy Sonic and Fluffy Tails, although a quick glance at their mod page doesn't show Persona compatibility and their character select screens sorta make them seem like they're just Sonic and Tails reskins. Still, might be cool.
I hope this is helpful, and if anyone wants to add anyone I missed that would be appreciated. (Also I hope the mention of Gamebanana for this modded game mode is okay?)
-edit: Point and Fluffy are missing Persona Summoning sprites. I suppose that's what I get for loading in a mod without official support. Too bad, their head tracking would be really cool for this.