Yo, game mode for you and co, you start with a pu sample team and play in nu, each time you KO a pokemon in the tier your playing in you add it to a team in teambuilder. Once you KO 6 mons in the tier you are able to play the next tier up with the six pokemon you knocked out. So if you KO 6 nu pokemon you go to ru, ru->uu, etc. If you dont ko 6 mons on the first try you can substitute them in to the team you are