[New moves, flora, animals, and mutations!]

I feel the fused hindlegs would be a benefit for swimming.

Maybe the nichling has to be born in "shallow" water to avoid taking damage?

[old age / elders (and a few other things)]

Agreed! Older nichelings would look nice with graying muzzles.

[Digging for Moles!]

I really want to catch those moles. It would be great if we could dig after them-

Maybe enhance the digging paw to this end?