As we have characters who are obtaining Mythical (not legendary) Pokemon through life-changing events as of late (re: Mallow and Nozomi), this is allowed. I'll have to have a rundown of the plot obviously from the tabletop event but I'm sure conferring with the other mods will give an all right with this situation I'm sure.

It would have to work along with the rules a Shaymin follows in the Anime more or less.