Zangoose's disdain for Seviper radicalizes when one fuses with Yamask to become Yagoose. Yagoose tend to have either an even more ferocious and vengeful obsession with Seviper, or grow oddly attached and affectionate towards Seviper instead.
When it battles, it stands on its hind legs and attacks with its sharply clawed forelegs. These Pokémon arose from the spirits of people interred in graves in past ages.