Joel McHale as Elliot. He was supposed to marry Giselle, but abandoned her due to new emotions. In the end, he and Giselle end up getting married anyway after he finally manages to profess his love for Giselle. Mike Epps as Boog. He also leads the rescue mission to save Mr. Weenie. Cody Cameron as Mr. Weenie. He is a German dachshund. He was captured by Fifi and the pets, leaving Boog, Elliot, and the other wilds to go rescue him. Jane Krakowski as Giselle. She is Elliot's fiance who is scared of getting married. However, in the end, she and Elliot end up getting married after Elliot finally professes his love for Gisele. Billy Connolly as McSquizzy. He joins in the mission to save Weenie. Crispin Glover as Fifi. He is an ill-tempered toy poodle who is often annoyed by his companion, Roberto. Fifi has a deep hatred over wild animals and slowly begins to lose his sanity after his forehead gets burned during a chase. Danny Mann as Serge. He joins in the mission to save Weenie with Deni. Matthew W. Taylor as Deni / Buddy / Ian, one of the main protagonist. Except for Ian, they join in the mission to save Mr. Weenie. Steve Schirripa as Roberto. He is Fifi's dim-witted companion who usually annoys him. In the end, he is reformed and becomes friends with the wilds. Fred Stoller as Stanley. He is a pet cat who is constantly annoyed by Roger. In the end, he is reformed and becomes friends with the wilds. Sean Mullen as Roger. He is an intellectually disabled cat who often annoys his best friend Stanley. In the end, he is reformed and becomes friends with the wilds. Diedrich Bader as Rufus. He is a Southern dog who is Charlene's boyfriend. In the end, he is reformed and becomes friends with the wilds. Olivia Hack as Charlene, a Western dog who is Rufus' girlfriend. In the end, she is reformed and becomes friends with the wilds.

Answer this question based on the passage: who plays roger the cat in open season 2? Let's have some stream of consciousness first.
The important part for answering this question is: Sean Mullen as Roger. So, the answer is Sean Mullen.