When performed, Mario launches a pair of spinning flames from his hands that grow larger and larger as it travels away from Mario. Opponents caught in it are dealt multiple hits of flamedamage (5%per hit) each with weak knockback that drags them along its path. It can be a one-hit KO if performed at the correct time and direction.
Mario Finale resembles the Ultra Flame attack from Super Mario RPG: Legend of the Seven Stars. The attack involves Mario shooting a barrage of powerful fireballs that damage all the enemies on the screen. Aside from this, the move has no clear origin, but rather takes inspiration from Mario's pyrokinetic abilities he obtains after collecting a Fire Flower.
Mario Finale was one of the two special moves that were considered "Final Smashes within Final Smashes", the other being Genki Dama from Super Saiyan Goku. Both attacks are used by Final Forms and could only be used once per transformation as they drain the users' energy and revert them to their regular form. Mario Finale, however, required manual charging while Genki Dama is charged automatically.
Prior to v0.5a of the SSF2 Demo, when Fire Mario fully charged a Super Fireball and released it, it would become a much smaller version of the Mario Finale. Though it was not nearly as powerful as the new one, Fire Mario would not have to transform back into regular Mario.
In v0.8a, a bug gave Mario Finale an advantage in that it could be used as many times as the player wanted without reverting Fire Mario into his regular form, as long as it was used on the ground. However, it could only be used for racking up damage and it would rarely drag the opponents off-screen. This bug could not be used if Fire Mario performed the attack in midair.
In v0.8b and v0.9a of the demo, Mario Finale could be cancelled if an opponent shielded the attack. This makes the whole attack disassemble.
The sprite of the rotating fireballs was originally that of the Speed Burner from Mega Man X2.