Hint: Battery combinations:

Boomer: Air + Air
Bulbot: Hyper + Hyper
Bulbot: Hyper + NiCD
Bulbot: Mangan + Air
Bulbot: Mild + Mangan
Bulbot: NiCD + NiCD
Bulbot: Normal + air
Bulbot: Normal + Mild
Bulbot: Normal + NiCD
Bulbot: Normal + Normal
Fighter: NiCD + Air
Granite: Mangan + Mangan
Hippon: Hyper + Mangan
Leaky: Mild + NiCD
Meddy: Mangan + NiCD
Sumito: Normal + Mangan
Ta-daa: Hyper + Mild
Timzup: Mild + air
Wobble: Normal + Hyper
Woolly: Hyper + Air

Hint: Bulbot:
Bulbot is the worst Robopon in the game. It has low HP and attack.