Janemba and Gogeta are a pretty cool addition to the game, considering both have been of dubious canonicity in the Dragon Ball universe for many years. Janemba, for example, just like Broly, is a movie-only character, who appeared in the movie Dragon Ball Z: Fusion Reborn.
Just like Broly (the original Broly, not the Dragon Ball Super version), Janemba has often been mocked by most Dragon Ball fans for having one of the weaker films, but that presents a slight chance for a future look. he.
Prior to the release of the Broly movie for Dragon Ball Super, Dragon Ball FighterZ had a pack of fighters that not only carried Goku's father Bardock, but also the original version of Broly. Broly would later scale his previously controversial image of him (where he was mocked for being stupidly powerful and having a terrible reason to hate Goku) into a much better character.
If we go the same way due to Janemba's vision in Dragon Ball FighterZ, a Janemba movie may be in the works, although nothing has been said by Toei Animation or Akira Toriyama, so Janemba may be included in the game just for fun.
Along with Janemba, the ending of her teaser (which you can find here) also hinted that we would get Gogeta next, a logical step considering Gogeta's first strong demonstration (at least in the current canon) in the Dragon Ball Super: Broly movie.
Either way, you will be able to add Janemba in Dragon Ball FighterZ on Thursday 8th August