Marvel Tōkon: Fighting Souls has a fairly substantial character roster at launch. The base game features a total of 20 playable heroes and villains. You can choose from preset teams to complete the story mode, or put together your own teams for the other modes. However, the game also has a secret character: Champion, the final boss of the Episodes.
Champion will not be available by default when you first start playing. However, you only need to meet one very simple requirement to use him in the different game modes.
If you want to play as Champion, all you need to do is complete any one of the Episodes. Once you have finished one of these storylines in its entirety, Champion will become playable.
You may be wondering whether it is possible to unlock Promoter as an additional character, since you face her in several "fights" throughout the story mode Episodes.
The short answer is no, she cannot be controlled through any legitimate method and serves only a narrative role, despite having her own character model for battles.
