I'll do mine in comments, as should you

Last breath phase one

Or deltarune Megalovania

(for the collector)

Eggy: Interstellar retribution
Omeletta: Canon swap sans theme
Edgyhead: Slaughter in the potlight
Starved Eggy: Assured prey
Egg-alomaniac: Red Megalovania

I really don't like how all of these are from aus that I don't know

Just regular STMPWYFS would be perfect for eggy

Knifeboi would have song that might play when you fight sans

Thunderpug would have ASGORE

Zanthor would be Metal Crusher
Beldum would be ASGORE
Puppet Master would be Megalovania