ah, i get it. so it has to have an interchangeable form in order to actually share it so long as the requirements are able to be met. so id assume its the same with megas?(i mean, darm scenario is the same conditions for megas, where the form change is activated ONLY via in battle) so if something like gyara could obtain fighting moves, IF it has the requirements of which a form change could occur (holding a mega stone). oddly enough, that would add a weird depth into the meta, where maybe having more then one mega could be BENIFICIAL to the holder. (for example, gyarados holding a mega stone would enable it to run heal order, something lefties couldn't do) id imagine that would be pretty cool.
i mean, if rotom doesn't have to be in the correct form to use its moves, i don't see why megas NEED to mega evolve to use theirs, they just need to have the stone, so the POSSIBILITY of it changing is there.
plus that sounds cool, sacrificing a potential item slot, for the ability to run MORE moves. bulky gyara would appriciate it, that's for sure.