ShadowForce720
Well-Known Member
Normally the sources are combinations of some other energy or matter (usually from a legendary pokemon) combined with human/pokemon energy or other matter. The "big stone" was an anime-only thing wasn't even fully explained there. In the games Mega Stone are theorized to be mutated evolution stones exposed to the power of the Ultimate Weapon 3,000 years ago (the power haivng come from many pokemon, but especially Yveltal/Xerneas), but where the stones enable the mega evolution, the power for it also comes from within the pokemon and the bond with the trainer (mega evolution is partly described as a pokemon releasing all its potential at once). Z-moves likewise have multi-faceted sources, the energy coming from the trainer and the Z-crystal, the Z-rings having come from pieces of Necrozma's body that it shed over the ages (if I recall right).
Actually if I recall right although it's true that Z-crystals and Z-power came from Necrozma it's not true that it was because it was shed pieces of it's body because that would imply that it was doing that naturally, no what was basically a case where Ultra Necrozma got attack by the ancestors of the Ultra Recon Squad who tried to control and in the process even though they didn't intend for it to happen they caused Necrozma to lose a part of itself which turned it into the husk that we see in Sun and Moon and Ultra Sun and Ultra Moon.The missing part of it wound up being spread out and scattering through Ultra Space and effect the Alola region which got directly hit by it which caused the formation of Z-crystals along with pokemon and perhaps trainers and people absorbing the energy into their bodies allow the pokemon to use Z-moves.
Also some of the pokemon absorb so much Z-power that they became Totem Pokemon, while it seems like unexposed trainers and Ultra Beast wind up getting exposed to Z-power and absorb a large amount of it when they past through Ultra Space which is why all the Ultra Beast tend to have the ability Beast Boost, and from what it seems it seems like the Z-power also spread to part of their world effecting them even if they never enter Ultra Space.
So in the end this is why Necrozma always appears to be in so much pain, and anger and feels so much hunger when it's in the form that we see in Sun and Moon and Ultra Sun and Ultra Moon before it takes over Lunala, Solagaleo, or regains it's true form Ultra Necrozma.