>>41647846Ultra isn't a bad choice. It's been available in every mainline game so far. RBY, GSC, RSE, FRLG, Colosseum, Gale of Darkness, DPPT, HGSS, BW, B2W2, XY, ORAS, SM, USUM, Pokemon GO, Let's Go Pee/Eevee, and SWSH.
However, in Pokemon GO, you can only use Premier balls to catch Raid Bosses and other legendaries. You can't catch them in Ultra balls. When you transfer your GO Mewtwo over to Sword/Shield, it'll be in a Premier ball.
