Bee + Plasma Casters + any class mod that increases magazine size or grenade damage + Tediore Allegiance relic. I prefer to use a gunzerker or commando to farm bosses. I use fire element plasma casters for Hyperius and shock for Pete.
"If there's grass on the field, have sex with it." -Confucius GT- TheLoveFister
Kraz ... if you're using a baby maker and it's not doing much, you're doing something wrong. It's not the shots that hurt him, it's the reload. Add the Bee shield and you should be able to take Pete's shield out in a matter of 20-30 seconds easy.
Using a gunzerker to farm hyperius. The bee plus babymaker. Using a siren with the ruin skill to kill pete. Really getting a lot of crystals. The seraph weapons aren't really worth it though (outside of the relics and meteor shower).