Hm. Let's see here if I can guess about Scary Monsters from what I know about SBR, and JoJo in general.

Let's see. I've heard Dio Brando from another universe, so that's probably who the Stand user is, judging by how John menitoned D4C's alternate universes. The Brando's are almost always antagonists, and the antagonists always have time powers. Time reset, acceleration, and reset have all been taken... I'm gonna guess slow down time?

Also, Johnathan with a Stand would have been cool. I wonder what Speedwagon's Stand would have been though?