When encountered, Master Green attacks by skidding across the ground and jumping around, eventually creating sparks or sending an electric shockwave across the ground. After the shockwave, he throws an electrical star towards Kirby, which he can inhale and exhale back at Master Green. He can also jump into the air and throw stars from there.
Master Green is a big jellyfish imbued with electricity. His head is disc-shaped with two small black eyes. From beneath his head, eight thick tentacles hang down. The official artwork depicts him as yellow, despite his name. In the Kirby of the Stars Pilot however, he was green with greenish-blue tentacles. Although he is a jellyfish, he shares more traits with cephalopods than cnidarians. Master Green is also not transparent like regular jellyfish.