>AZ's eternal flower shot a laser beam to space
>laser hits a meteorite, mutating the dormant space virus within it
>meteorite eventually ends up on a collision course to PokeEarth
>Mega Fug shatters the meteorite, releasing the space virus within
>it reacts to Mega Fug's mega energies, completing its evolution into deoxys
>deoxy's stats are extremes, just like the stats mega pokemon get
>the core is its mega stone