They come in big waves
http://www.nintendoworldreport.com/news/46173/pokken-dx-adding-new-fighters-assists
More challengers are about to enter the Pokken Tournament arena.
Today's Nintendo Direct featured the announcement of two new playable Pokémon as well as four assist Pokémon in a paid Battle Pack. Aegislash and Blastoise will be full fighters, while Mega Rayquaza, Mimikyu, Mew and Celebi will be Assist Pokémon.
The new characters will drop in waves, with Aegislash, Rayquaza and Mimikyu releasing on January 31 and Blastoise, Mew and Celebi following on March 23. The Battle Pack will be available today and include additional avatar items.
