Luigi runs the Ghostbuster gauntlet

luigi fills in for the new guy to bust some ghosts does he complete this small fry task...

yes

Equipped with a proton pack, Weegee could do more than the team could ever do...except defeating Class VII Deities. He'd still need to cross the streams for that, probably.

With the Poltergust? He gets stomped horribly. Unless it has the same properties of a Ghost Trap, in which case he could have the team weaken ghoulies with Proton bursts, then suck them right up.

he can upgrade Poltergust same as the ghostbusters

So you're saying he has a proton pack combined with a mobile Ghost Trap? Yeah, Luigi soloes the game until he had to cross the streams.

NEVER cross streams

Luigi jumps on Stay Puft's head and coins come out.