For me here's what I would go with.
- All Putties
- Tengas
- all Cogs
- Piranhatrons
- Putrid Pods
- all Chromites
- Quantrons
- all Craterites including the Leader and the Giant
- Stingwingers
- Swabbie
- Cyclobots
- Kelzak Furies
- Tyrannodrones
- Blueheads
- Orangeheads
- Lava Lizards
- Chillers
- Rinshi
- Grinders
- Moogers
- X-Borgs
- Bruisers
- Kingsmen