am i the only one who cant use them. i just battled someone with all ubers which includes arceus, palkia, rayquaza, mewtwo, girentina, and shaymin. but when i use even a rotom it told me to change my legendaries. and my pokemon are legit too.
That happened to me too! I onced fixed it. Have you beat story mode? I think you have to beat certain colloseums certain amount of times to unlock the use of certain legends.