If you don't see the Team button on a Pokémon when you're viewing your list of saved Pokémon, it means they are not legal yet because the minimum number of required fields isn't filled out yet. Go back and edit that Pokémon, filling in any missing required fields.

The required fields are:

  • Pokémon
  • Level
  • Gender
  • HP
  • Attack
  • Defense
  • Sp. Atk
  • Sp. Def
  • Speed
  • Ability
  • At least 1 Move