When Lucario activates its Final Smash, it will shout "Max Aura!", then transform into Mega Lucario.
During this state, Mega Lucario's aura attacks deal 1.8x the base damage regardless of Lucario's current damage. Unlike most transformation Final Smashes, this state does not render Lucario invincible; it will gain super armor and immunity to grabs, but will take half damage from attacks and can be footstooled during its duration. Attacks that connect with Lucario will not cause it to flinch or get knocked back in any way, but they will decrease its transformation time and cause it to transform back to normal sooner.
Mega Lucario can be affected by Super Mushrooms and Poison Mushrooms, but like all the other transformation Final Smashes, it is unaffected by Metal Boxes. Also, Mega Lucario lasts the longest of all the transformation Final Smashes when playing at normal speed, reverting back to Lucario after 14 seconds have passed.