FIFA Street 3

LEGIT:
Play thru the FIFA STREET CHALLENGE mode. This team will eventually unlock. It unlocks after you complete the “ All Star Challenge ”, which is the 8th Challenge within the FIFA STREET CHALLENGE mode. Once you have unlocked that team, all you need to do is simply play as the team. This works in any game mode.

FUDGE:
Now this is the ultimate fudge of all. You never actually have to ever play a game in the Fifa Street Challenge Mode. Go to an Online match, choose Playground Picks, either Ranked or Unranked. Now go & find someone that is playing as one of these teams. You will unlock the achievement for playing as this team at the end of the match.
This is completely fine, because the Playground Picks game acts just like it sounds. Whoever is the host gets to choose what team BOTH of you use. If you don’t have the team unlocked, don’t sweat it. You can still join the game. Playground picks starts with the host choosing a player on the team that will be on their team, then you choose, he chooses, you choose, etc… Once the teams and lineups have been decided, proceed into the game, complete it, and achievement unlocked! This is why when boosting/fudging this game is very possible for less than 5 hours completion.
NOTE: For the DLC ones, you have to be sure that both you and your opponent / boosting buddy have the DLC pack.