Kid vs. Kat (2008)

Ten-year-old Coop Burtonburger's life takes a turn for the worse when his little sister, Millie, brings home a mysterious stray cat who, in reality, is an evil cybernetic alien in disguise. To make matters worse, neither his family nor anyone else believes him, except for his best friend, Dennis. Now, Coop risks his life every day as he attempts to foil the cat's diabolical schemes and prove to the world that the family pet is an evil mastermind.