Enemies that defy logic are the worse to get involved loool.
Ganesh lost because he used a low attack first, you gotta go all out to defeat him (like the sea king did) and Nyan didn't put much effort either, so my theory is that as long as he can withstand the first attack he will adapt so yeah... Don't go easy on him.
A welcomed improvement from previous chapters! If we can't see Saitama for obvious reasons at least let us watch the other S heroes and have fun!