I'd make pokemon, but I've add a bug/water type, though some other ideas would be, making a sonic game with more than one playable character (srsly wtf do they think they are doing, none wants to play as sonic, mine would include all the characters from ADX to Current, and more)
One more idea would be to make my own game with all original characters, but it would be a fantasy about twins (brother and sister) with special eye powers, Maybe make it one where you create your own character and play through the game either with the twins or against them and then make it have online capabilitys. Meh Idk didn't really think much about this idea yet.