u/Aware-Measurement750

Giratina in pokemon platinum

Venom in lego marvel superheroes

Elder guardians in Minecraft (this one still gets me sometimes lol)

Doom enemies will sometimes fight each other (doom)

Minecraft mobs will attack each other if one accidentally hits another mainly skeletons (Minecraft)

In horde battles there can be a different pokemon that the other pokemon are rivals with and they'll fight the example here being zangoose and seviper (pokemon)