This is a series 7 BSS competition with ONE normally banned Pokémon allowed. Similar to the Battle of Legends recently, except singles instead of doubles.
Bring 6, pick 3. Singles
All Pokémon become level 50 in battle
All Pokémon available in Sword and Shield, the DLCs, and Pokémon Bank transfer allowed EXCEPT:
Mew, Celebi, Jirachi, Victini, Keldeo, Genesect, Diancie, Volcanion, Magearna, Marshadow, Zeraora, Meltan, Melmetal, Zarude
Each team limited to ONE of the following:
Mewtwo, Lugia, Ho-oh, Groudon, Kyogre, Rayquaza, Palkia, Dialga, Giratina, Zekrom, Reshiram, Xerneas, Kyurem, Yveltal, Zygarde, Cosmog, Cosmoem, Solgaleo, Lunala, Zacian, Zamazenta, Calyrex
Not entirely sure what it has to do with dragons, but there you go.