Tom and Jerry: The Movie
I love this movie and think it's underrated. However it would've been better off as its own thing and not having Tom and Jerry, since they are admittedly portrayed nothing like their TV versions, aside from the scenes that don't have anything to do with the plot. When I first watched it as a kid, I had no idea them talking was a one-off thing since I had not seen the show at the time (and I guess I didn't pay much attention to the scene where they begin talking and are surprised about it). For that reason, I can't hate this movie. But I would agree that being an original thing would've served it better than basing it on a show with a completely different tone.