Or just #1 if you don't wanna write allat

Octoling

Osmosis Jones (Ozzy&drix Gameboy advanced game makes is possible but unlikely)

Waluigi (the goated one)

Beat from JSR (he's literally the sonic equivalent with Splatoon inklings being the Mario equivalent, so with JSR being from Sega it makes it likely that we'll have competition for the splatoon characters)

Lego Mario (funni)

Waluigi
Conker
The monkey from super monkey ball
Toad

Waluigi
Funky Kong
Louie (as olimar alt skin)
Protagonist from Pikmin 4 (as alt skin for olimar)
Paper Mario