CAMERUPT has a volcano inside its body. Magma of 18,000 degrees F courses through its body. Occasionally, the humps on this POKéMON’s back erupt, spewing the superheated magma.
The humps on CAMERUPT’s back are formed by a transformation of its bones. They sometimes blast out molten magma. This POKéMON apparently erupts often when it is enraged.
A POKéMON that lives in the crater of a volcano. Every 10 years, the volcanoes on its back erupt violently. Research is under way on the cause of eruption.
If angered, the humps on its back erupt in a shower of molten lava. It lives in the craters of volcanoes.
It has volcanoes on its back. If magma builds up in its body, it shudders, then erupts violently.
— Pokédex entries (via PokeAPI)