Seismitoad is a bulky, blue, bipedal toad-like Pokémon. Its underside and the speaker-like bumps found on various parts of its body are cyan with black edges around the belly. Its hands and feet have three bulbous digits. Additionally, Seismitoad have red eyes, cyan adornments on its legs, and a long tongue. The various lumps on its body have varying capabilities. The ones on its head can shoot a paralyzing liquid, while the ones on its hands can be vibrated to increase its punching power. It can also vibrate the lumps as a source of torment for its opponents.
Seismitoad appears to be a combination of a toad and a loudspeaker. The spherical "speakers" on its body might be inspired by the "warts" and paratoid glands found on most toads. Alternatively, inspiration may come from the common Surinam toad, an aquatic amphibian whose backs are covered in pockets that hold its eggs. It may also be based on a goliath frog because of its massive size. Its Pokédex entry mentions the fact that it creates vibrations underwater, which is also similar to the common Surinam. The two bumps on its head may be based on the bells of a traditional alarm clock.
Seismitoad's punching ability can be explained in the same way as a person being able break glass with their voice. Seismitoad's hands will vibrate with the resonant frequency of the object about to be hit, causing extra damage when hit. This can cause devastating effects on objects; for buildings, it can cause them to sway or collapse entirely, also known as a resonance disaster; for living creatures, it could cause internal organ damage to the extent of possibly rupturing them.
Seismitoad may be a combination of seismic and toad.
Gamageroge may be a combination of 蟇 gama (toad) and ゲロゲロ gerogero (onomatopoeia for frog croaking).