Since I figure nothing will come of it, I might as well post the idea that I had for an indie fighting game roster.
Top row: Quote (Cave Story), the Goose (Untitled Goose Game), the Knight (Hollow Knight), Crow (Nefarious)
Middle row: Cuphead (Cuphead), Sans (Undertale), Sash Lilac (Freedom Planet)
Bottom row: Madeline (Celeste), Shantae (Shantae), Meat Boy (Super Meat Boy), Shovel Knight (Shovel Knight), Cadence (Crypt of the NecroDancer)
I had some ideas for characters that I left out because their mechanics wouldn't work well or wouldn't be fun to play (V from VVVVV, Dandara from Dandara, Tim from Braid), they'd be a nightmare to animate if I ever actually tried it (Octodad), they wouldn't mesh well with the rest of the line-up in terms of design (Miriam from Bloodstained, Juan from Guacamelee - picking them would make most matches seem like fighting Yoda in Soul Calibur 4), or I wasn't sure if they qualified as indie or not. (Ori from Ori and the Blind Forest)
The final boss would be Satan from the Binding of Isaac, or Mega Satan from the same game if I couldn't figure out how to get a two-stage battle going.
Admittedly, I haven't played much of Shantae or Crypt of the NecroDancer, so I'm not sure if there are better choices out there. (I died on the first non-tutorial level of NecroDancer, so I feel like it's a hard game; not sure if Cadence of Hyrule is more accessible, or if there's something that I'm missing)