Part of me wonders if this was a mistake, or if whoever wrote this left a mistake or two in. Mainly the idea that right after Bulma, we got "Boo." Of course, you can say "This is how it was shown in..." but if we have already established "Majin Buu" and the way the name is spelled, that would mean that either a name was misspelled or this was a mistake and the person who wrote this meant to say that you would see Bulma in the game, but not play as her.
All that said, would Bulma be a nice inclusion? Of course she would. Only problem left from there is that you would be taking certain liberties as to how she would conduct herself since we never really have seen her actually try fight anyone. Certainly there's nothing wrong with making her something like a "Never before seen" character and how she has a mech suit that lets her hold her own against Goku and company.
I won't be against the idea, but they are definitely going to have to do alot of things to make it convincing.