Legend

Kennon: Once upon a time, there we're two pokemon. One gave eternal life, while the other turned pokemon into stone. One faithful day, the pokemon that gave life wanted the pokemon that gave death to stop. The death pokemon refused, thus beginning a war. A pokemon named zygarde realized it's ecosystem was in danger. When the two we're sealed away, not every last bit of they're magic went with them. Legend says when the ecosystem is in danger, that magic takes the form of mega zygarde.