Animatronic Mario is an animatronic husk that Mario was programmed into alongside the violent Spaghetti.exe executable file.
Animatronic Mario's personality is the same as regular Mario, but he can get hostile immediately if the spaghetti.exe program is operating.
The spaghetti.exe program was created by the William Afton for Animatronic Mario to kill anybody who gets close to him. His program is similar to all of the other animatronics, except it is about spaghetti. He kills them because the program works by telling Animatronic Mario that the person who gets too close to him is spaghetti, and so he kills that person with whatever he has. In the case of the video R64: Revenge of Freddy's Spaghettria, Animatronic Mario thinks that Luigi is spaghetti because of the program, and so he tries to kill him with a rocket launcher, but fails because Luigi blows Phantom Balloon Boy out of his Poltergust 3000 and hits him in the face, which causes a critical error, and it also crashes the spaghetti.exe program, preventing it from operating again.
Animatronic Mario is an animatronic version of Mario, with a missing left eyeball, a missing right eyebrow, and is missing skin from his entire left hand plus a few more patches of missing skin from his body and from his legs. In The Grand Mario Hotel and SMG4: Freddy's Ultimate Custom Spaghetteria, Animatronic Mario reappears in a more repaired state.
This is where Animatronic Mario makes his debut. He tries to kill Luigi, but is stopped by him after he manages to break down the spaghetti.exe program that William Afton programmed into him. He tries to get his body back, but William refuses to give it back, causing the animatronic to shoot countless Bowls of Spaghetti at him. Later, he and Luigi manage to defeat him after William gets inside of Springtrap, and gets killed because of a malfunction. Animatronic Mario destroys the door with a bunch of TNT, but however it destroys the whole building too. He manages to find his body, but decides to give it to Professor E. Gadd.
Animatronic Mario makes a small appearance in The Grand Mario Hotel, only in a more repaired state.
After being chased by Mangle, Mario is smacked on the head and sees himself in the form of Animatronic Mario. After freaking out, he has a brief encounter with Phantom Freddy and both screamed in panic. He then ran into Springtrap, who became infatuated and proposed to him. Mario rejected Springtrap, causing the creature to smash Mario through a wall, now back in his normal state. It's unknown how Mario was transformed or how he changed back.