>>20758836"Commonly" is a relative term here. Certainly there's been a long sustained movement within the Heonn League for the recognition, and an application for a fairy gym was in serious consideration at one point (perhaps they'll reconsider on the next vacancy). But the movement only gained serious traction among the League and some of the more experienced trainer; the rest of the Heonn population was by and large unconvinced and/or biased towards the existence of the fairy type.
>>20758955Your question is the source of an enormous amount of speculation, debate and controversy among the scientific community, the largest I've seen since the Coronet Incident. The general consensus is limited to a. its existence b. requires the use of a "key stone" and a corresponding "mega stone" c. a second party with the key stone seems to somewhat help with the process. Basically everything else is uncertain at this point. Professor Sycamore and Champion Steven have been intensively studying the Mega-phenomenon, they might be able to provide some more insight.
