Invasion

Cast(in order of appearance):Calvin Jacobson,Hobbes Jacobson,Zoe Jacobson,Andy Adams,Sherman, Socrates,MTM, Galaxoid,Nebular, King Stor, Rowan,Elliott, Holographic Retro, Retro, the Plantonians,Commander Nesbin,

Plot
In the final Tv movie before the true finale when ankor is invaded Galaxoid and Nebular have to ask the only people that can save them, and what matters worse the gang have to deal with retro again.

Trivia

 * This is retros second appearance and has gotten more evil since he was imprisoned on ankor by Calvin and Hobbes, and he destroys Holographic Retro making it have its final appearance.
 * For Half of the episode after calvin tests a memory device for sherman he goes back to his original personality from the first season due to temporal amnesia
 * at the end of the movie retro returns to earth and talks to a certain alien in prision