Oh god, that means Clowpy first led Utsuho to madness in order to acquire the Control Rod??!

I can see you were quite ambitious for trying to make a fighting game. Well here's my two cents about this:

-A fighting/action game is a very detailed kind of game, where feedback is very important, taking on the form of visual cues like hit effects, pain sprites, wind-up sprites.... and audio cues with of course hit sounds, whiffs, maybe some windup moves. And there's also the famed "hitstun", where a connected hit is paused for a couple frames to give the hit emphasis.

-If you want to put projectiles in a comboing game, consider putting in slow projectiles too which are easier to coordinate attacks with.

-The camera is important too. You might want to have only the characters at the edge of the screen and not capture the whole playable area, so that the characters' actions are more visible. In the case of a singleplayer action(/platformer) zoomed out camera is more acceptable as long as you can see what your character's doing. In your game, the actions were visible enough so no worries here.

What I'm trying to get across is: a fighting game in 3 days is bound to have only a small scope. Nevertheless, it's a good enough prototype you managed to get out in the time limit. I featured it in my video here~:

https://youtu.be/bFHWSZ1BOBw?t=1275

The sprite art is excellent!

It looks promising! poor meiling...

"How this game fulfills the theme: Clownpiece + Utsuho combo" lol

Good game, but I disapprove of bullying Meiling >:(

meiling and clownpiece spritework is rad, i like how jumping changes both attacks a bit. pretty simple so not too much i can say but i getcha, time limits can make you cut a lot

Well, Clownpiece controls alright. I do like the attacks but there's heaps of cooldown delay (which for a fighting game idea would be pretty painful. Though the diagonal attack is pretty bad but that's the only one I'd say for sure is. )
The idea is goofy but endearing for sure, I could totally imagine Clownpiece just trying to blow away Meiling in this absurd battle.
But yeah there's no fight so it's hard to give more feedback than that.

Me and Cathulu also tried to make a fighting game for our combo (Ironically we had Meiling as the main protagonist, and she was kicking fairies and even their danmaku right back at them, while shooting giant hadokens ).
So I know how you feel given the time crunch affected us putting out everything we wanted to for sure. But hey, this sort of thing is really fun to do even if it's rough. I hope to see your game fleshed out in future if you ever tackle it. 
If you want to check ours, link's below. Tell us how we went too :D 
https://itch.io/jam/touhou-jam-6/rate/912501

And goodluck in future.

The amount of spritework done in a day (at least I think from your description) is really impressive. I hope to see this idea get expanded upon in the future.