Return: as a character based off shippings, Koi initially screamed Attract to me in terms of moveset, but then I changed my mind over to Return since I do believe that she sort of follows that "generally cute but can still kick ass" archetype. this move is surprisingly powerful when a high friendship is involved, so I imagine it being able to hit pretty hard when used in the presence of one of her loved ones. it also highlights Koi's generally wholesome character, since I always saw the concept behind Return as really sweet and that type of move that hits you in the feels haha-
Sketch: as... out there as it is, I can see Koi using this move to better accommodate herself to the various universes that she gets herself into!! for example, maybe in a universe focused on fighting, she learns a more offensive-based move to better protect her loved ones in dire situations; however, she'd likely replace Sketch with a status move in a more peaceful universe. she seems like a flexible character, so a flexible move like Sketch comes into mind!! (+ she's fairly associated with art/creativity, hence why I chose this over something like Assist or Metronome.)
Water Gun: to be... completely honest... Koi literally makes me think of a fish, and fish are 100% Water-type by association, so... quintessential Water-type move it is lmao. plus, it's more towards the cute side of things, and since Koi is overall a cutesy character based on her headcanons in her bio. the only reason I chose this over something like Bubble or Bubblebeam is that I don't see her as a particularly offense-based character, but nonetheless, a move that at least packs some punch would be appropriate at times.
Sing: one of Koi's headcanons did mention that she sings out loud when a favorite song of hers comes on, so... *jazz hands* there was also another that stated that she hums songs while working on things, but I think the former headcanon is stronger evidence haha- I actually don't see her using this move intentionally a lot of the time, mostly because of the whole sleep effect that it has. still, it does make her 100% adept at lullabies imo...
---
- dfjhvfhuv oh hell yea I love that tbh?? honestly the fact that it's super status-based and not at all offensive (with Dazzling Gleam being his only strong move wheeze) is actually a really nice touch!! though... maybe battle-wise... Rage and Follow Me could be an interesting combo... :3c