Thunder and Storm

From Mother - Wiki on Neoseeker

Thunder and Storm is the boss of the Cave of Pink Cloud. As their name implies, and as can be assumed by the enemies inside the cave, T&S are of the lightning element. They appear as a yellow, young eel, and a white, old eel tangled together. The old eel holds a plant, while the young one holds a lightning bolt.

Battle Information

Thunder and Storm attack with lightning attacks. The Franklin Badge on your weakest character, which is probably Poo is unnecessary, but useful. They attack with Mr. Carpainter's and the Kraken's Crashing Boom Bang attack. It'll most likely make contact, so be prepared. Have Ness ready to heal if need be. Otherwise, just attack. Conserve your PP. Their weakness is PSI Flash, but it's not necessary. Paula should use her highest form of PSI Freeze. At level 46 she learns PSI Freeze Ω. It should do around 500 points of damage. Have Jeff use Bottle Rockets if he has any. If not, use other items, and attack. Poo should use PSI Freeze. At level 33 he will learn PSI Freeze γ. Unleash your strongest attacks and the eels will fall. Be careful, if they rush in and intertwine with you, it'll cause massive damage. Without any grinding, only Ness has a chance of surviving. Sometimes they may summon a storm, which is basically their version of PSI Flash. It'll cause some status ailments, and it might even kill a few characters. Then again, it might do nothing. If you're lucky, you can go the entire fight without taking damage. If Paula and Poo solidify Thunder and Storm each turn, then it'll only take about five turns or less to win.