Fish

When I'm fighting them apparently sans beats me XD

but undyne cant dogde so all of sans atracks will hit her and sans can cheat by not doing turns.

undyne, sans has one HP and an dodge 25 attacks, undyne needs to use her attacks 26+ times

yep

Undyne: HAHA! So we finally come to fight.
Sans: Eh, I'd rather say no.
Undyne: You are NOT backing out of this fight!
*Fight begins*
Sans: *Dodging attacks*
Undyne: H-HOW!
Sans: I just have the skills.. *Summons blasters*
Undyne: what the-
Blasters: *Fire*
Sans: eh.

Undyne.