There are a lot of "ifs" and "maybes" when it comes to using someone else's Intellectual Property that I can't really answer. As long as you don't use somebody else's assets and clearly mark where your characters come from and who they belong to, this shouldn't be a problem for the purposes of the game jam. There are no prizes this year, so you've nothing to lose by entering it!
Yes, that is what i was refering to. Use pre-existing characters from pre-existing franchises clearly saying "Hey, this comes from X" and creating assets from scratch. Thanks for the clarification!
