In order to get this achievement you need to unlock all the characters from the base game. You DO NOT need to buy any of the character packs.
You can check which characters you're missing by going to the quick battle character selection screen and scrolling through the characters. The ones you still need to unlock will have the requirements listed.
That being said, you essentially need to do the following things to get the achievement:
- beat the single player campaign (all 8 tournaments)
- beat all 9 quick battles
- reach rank 33 in multiplayer (probably easiest boosted)
- have 7 different friend challenges (you need to be friends on xbox and then the little icon on the right in the main menu will allow you to challenge a friend, doesn't matter who wins)
If you plan on completing the game, the single player campaign, quick battles and the rank 33 in multiplayer, all have other achievements tied to them so you'll get these naturally when going for those:
For the friend challenge you'll need to setup sessions or message people who have the game.