After defeating the first of either Genesis or Oblivion, you'll be teleported to the Yamashita Farm, in the Mimiga Village. After a brief cutscene with Sue, Curly, and Booster, you will be given the ●BOOSTER v2.0●, allowing you to fly around faster, and in any direction.
After both Genesis and Oblivion have been defeated, you will be teleported to the island's Core. Balrog will be found nearby, and he will offer to trade your ●FIREBALL● for Curly's ●MACHINE GUN●.
Afterwards, head to the left to wind back up in the Revolutionarium. Make your way back to the Mimiga Village however you see fit. When you return, head to the Town Hall and speak with Booster to receive a key for a pair of new rocket platforms in the Chimney and Conduit.