Alright, let's do this Mega Man style.
spamwise- spamwise is the introductory boss, so he's easy to beat. Hit him with your Mega Buster enough and he'll go down. You get the "indifference bomb" for defeating him.
Honest Gamer- Honest Gamer attacks you using argument attack, which is easily countered with the indifference bomb you just picked up. Use it and pick up the argument attack for your troubles.
Jane - Jane hits you with her popularity beam and niceness bomb. Use the argument attack to destroy all her attempts at being nice. Jane drops the kindness gun upon defeat.
Dancer087- Dancer hits hard with his intellect and debate cannons. Kill him with (the) kindness (gun) and collect his super-intelligence ability for the next fight.
Dhampy- Dhampy uses his wackiness to confuse and amuse opponents. Cut through his fierce offensive by using raw logic (your super intelligence ability). Take the wacky sword that he drops.
Darkish- Darkish, armend with 200 paintball guns is one of the game's most challenging bosses. However, if you use the wacky sword to alter the course of space and time you can sneak past his defenses and hit him from behind. Take his paintball gatling gun after he falls.
Insom- Insom is armed with an entire (meticulously painted) Ork army. Use the paintball gun to ruin his hours of concentration and steal his now-camouflage Ork army while he's still distraught.
42- 42's "all the barbecue sauce" attack will destroy you in four turns (because this is now an RPG for some reason) but this boss battle is relatively easy. Just use the camouflage Orks to sneak into the barbecue cannon and deactivate it before boom goes the dynamite.
Hyper- Hyper, the game's final boss hits you with the most deadly attack yet--- bad puns. If you can survive the bad puns for four turns, then by all means use the all the barbecue sauce to win the game. They're really bad puns though, so be prepared. And may the fours be with you.