On serebii.net
"Battle Revolution Wi-Fi News
Update @ 21:04 BST: It would seem that, according to many people in some unconfirmed reports that Nintendo has not placed a ban upon the legendaries, but rather a glitch in the WiFi Connection system prevents your Battle Passes with the legendaries in from being accepted. According to a variety of reports, if you reset the Battle Pass, it should work, but we do not know whether this was an intentional thing and this is a way to get round it or whether it was actually a glitch. We'll keep you aprised on any further developments
Original Report
In a move that is likely to infuriate some, and yet please others, according to many reports across the community of which are not yet 100% confirmed, Nintendo has, as of today, seemingly banned Legendary Pokémon from being able to be used in a Battle Pass on the Battle Revolution Random Online Matches. This seems to be due to the massive amount of people going online with nothing but teams of Pokémon known in the community as "Ubers" such as people having a team of, for example; Dialga, Palkia, Mewtwo, Giratina, Lugia & Manaphy. This thus made the balance unfair for the trainers who were using their favourites throughout the game
It is unknown if Nintendo will re-instate the ability to utilise these Pokémon in the near-future, but for the time being, it appears you are free to battle with your normal non-legendary Pokémon on the Random Online feature. You're still able to utilise the legendary Pokémon in Friend Code battles however as well as the single player of the main game."
maybe just fixed the problem
