Paranatural/WMG

PJ only died very recently.
Recently enough to use up-to-date slang ("...then you screamed and totes fainted.") Maybe this is why Max's Dad got such a good deal on the Corner Store?

R.J. is some kind of supernatural creature
Especially supernatural, considering normal humans can see him. I base this on his eyes, which are weird even for this comic.

Mr. Spender's glasses are his tool
In the scene right before Max bats the... well, the bat, we see a quick set of pictures showing the other characters preparing to step in- Mr. Spender is holding onto his sunglasses, with what may be energy swirling towards it or out of it. It would also explain why it is that he's always wearing them.

Alternatively, his tool could be in one or both of his eyes, or be his eyes themselves.