Puff Up

Puff Up is 's Final Smash in Super Smash Flash 2.

Overview
When performed, Jigglypuff inflates slowly to an extremely large size, enough to cover the entire length of, pushing away opponents that make contact with it while inflating. Once at full size, it shouts "Jiggly!", dealing about 15% damage and extremely high knockback to any opponents nearby, which may result in a one-hit KO with the right conditions. After this, Jigglypuff quickly shrinks back to normal size, ending the move.

Origin
Although it doesn't originated from any of the  games, it appears to be based on Jigglypuff's inflating ability outside of the main games like in the anime and manga, which may also be based on its classification as the "Balloon Pokémon".

However, in Generation VIII, a similar mechanic was introdued in the form of Dynamax, which allowed the Pokemon to grow big akin to the Final Smash.

Trivia

 * This is Jigglypuff's only special move in SSF2 that does not originate from the Pokémon series, instead being original to the  series.