While Scizor is good against it generally, many people expect this and run HP Fire on Cress. Pairing a strong Ground type, or electric attack absorber who take a Hidden Power Fire is a good idea, for scouting for Thunder Wave or HP Fire. Once you know how Cress intends to deal with your Scizor, it becomes a lot easier.
Tyranitar is absolutely the most effective though. If you need an absolute deadset counter, Tyranitar is your Pokemon.