The puppet is a one-time minor character who only appeared in "Katz Under the Sea".
History
The puppet was seen talking to Courage, that he, for one, don't want to be in the submarine, which Courage agrees. For himself, he's claustrophobic. He can't stand being stuck in small places. Courage agrees with him. Then, the puppet's owner puts him away in the suitcase, which the puppet hates to be in. Katz's submarine does not allow dogs, so Courage releases the puppet out of the suitcase and disguised himself as a puppet to get in. And for the puppet, he gratefully thanks Courage and runs away from the submarine. He has never been seen or heard from again.