WMG / The Chosen Four

Wild Mass Guessing for The Chosen Four.

Reginald Jr. is a Time Lord, and Ness's backpack is his TARDIS.
Well, he can certainly fit a ridiculous amount of things in there, including a workshop and a swimming pool.

Jeff is a Technopath
If the other three have Psychic Powers, then why not Jeff? Given his affinity for gadgets, it makes a lot of sense.