2D Undertale style battle system

I made a cool little Undertale style battle system and would like some feedback on it!
I’m planning on redesigning the UI completely and using it in future projects.

Is there anything that should be changed?
Are there any flaws that I’ve left unnoticed?
Is there anything else I need to know?

I’m currently using Mettaton NEO as a placeholder opponent.
Here’s the link: Mettaton NEO - Roblox