Well, so I tested the Ranamon animations in-game, and... Well, shrunk down to the size it's supposed to be, it just looks like ass, to the point where she's practically unrecognizable. Well, that's awkward. And I don't have the time to try and experiment with pixel art, so...
I decided to "cheat".
Rather than a direct fight against Ranamon herself, she bails right before you enter her boss room (because Myotismon ordered her to, as he's genre-savvy enough to know when things are going south), and leaves you to fight two drones shaped like her hands while she mocks you with a gigantic hologram of herself.
The hands themselves move into various positions to attack, such as rotating in a fixed position in a circle around you while firing projectiles (requiring you to watch where you're moving to evade), or aiming at you from above and firing downwards while moving from side to side after firing. Zoe/Kazemon is trapped at the top of the arena, and you can free her to make her a co-op/AI partner before the fight ends, but you have to manipulate the arms to hit the teleporters to turn them on in order to reach her.
Still trying to work out an optimal setup for the camera, I might be inclined to just not have it fixed to any particular position, unlike other boss fights, since the arena is so big.
Yeah, not nearly what I was originally planning to do with this one, but that's what happens when you're constrained by a lack of art assets.