I think this game needs new guns, because its sort of limited to "handguns". (Although the Iron Slug is like a rocket launcher :D)
Maybe:
Shotguns (see thread: this game needs shotguns)
Grenade Launchers- sort of fires a bomb of some sort, with a reload after every shot: may use modified versions of already existing bombs, but with damage decreased (So you are not running around with some overpowered monstrosity that flings 5* bombs everywhere)
Rifles- Mostly Peircing or Split Pierce/damage type: Much like a handgun but with much graeter range and damage at the price of firing rate
(Will continue later)
The Pulsars and Catalyzers are basically that in two different fashions.
With Pulsars, you're shooting active blast bombs.
With Catalyzers, you're planting blast bombs on the targets.