Mega Evolution (Lucario)

Mega Evolution is Lucario's Final Smash in Super Smash Bros. for Nintendo 3DS / Wii U, replacing its previous Final Smash, Aura Storm, from Super Smash Bros. Brawl. Lucario transforms into its Mega Evolved form, increasing its aura power and allowing its attacks to deal maximum damage and knockback regardless of its current damage percent. For the duration of the Final Smash, Lucario cannot flinch or be knocked back from any attacks, though attacking it decreases the amount of time Lucario can spend transformed.

Mega Lucario is unaffected by Metal Boxes, as it never gains a metallic appearance, even in a Metal Special Smash. However, its size can be affected by the Super Mushroom, Poison Mushroom, and Lightning, which can increase or decrease its overall attack power.

On a side note, Mega Lucario is the only Final Smash fighter who can use custom special moves, but it's not able to use any equipment, as active Final Smashes disable them until they end.