Team Fortress 2 has a really weird hypothetical place in DriDim. And it has to do with the amount of characters. TF2 has 9 classes to choose from, 3 more than the max amount of characters allowed for a franchise. Now you may think that you could just leave a couple of the mercs out, only adding 6 of them.
BUT 9 is just small enough of an increase above 6 that it would seem kinda awkward to leave out 3 of the main characters. That's not even counting side characters that have large fanbases of their own. Maybe you could simply have 3 slots that each contain 3 classes.
BUT there is the problem of how you split them up. You could do it by the "offensive, defensive, support" way that the game already does, but you lose the biggest dynamics of Heavy and Medic and Scout and Spy with that way. That's not even considering the culture within TF2 about finding your "main" class, with it often having a large part in players's online identities and could run antithetical to cramming a bunch into a cart. Maybe you could have only a couple of characters share a kart.
BUT while this may be the best solution in my opinion, it still has a lot of problems. You could have a kart with Heavy and Medic, Scout and Spy, and Soldier and Demoman, with Pyro, Engineer, and Sniper getting karts to themselves. However, there's the issue of the side characters. Characters that people adore like Saxton Hale and Ms. Pauling would get the shaft and the franchise would only be represented by the core cast, making the inclusions feel more boring and dry. Plus, there's the issue of having to actually vote these characters in. Since the franchise submitter can only put in 3 characters, in order to get this roster, other threadgoers would have to submit the second half themselves. And then they would vote for the most obvious choices to round out the cast. Which could make for some very very boring submission and voting rounds.
Now, this is purely in the realm of speculation, but maybe there could be a 9 character "deluxe" franchise job. However, I don't really see this happening without the catch that racers would only be the type of content added. This would be pretty catastrophic in my opinion. TF2 has such a good-looking artstyle and a very unique array of items that would work wonderfully in the game and not having them would just sting. But this is still all just "what-if." What if the whole game was made out of pudding?
Or you could just put all 9 in one kart... that's pretty much the closest thing to the objectively worst idea that I can come up with and I kinda like it.