Although I don't really feel like getting into a Donphan vs. Relicanth debate as they both have their ups and downs and should be used for different reasons...
Unless something has extremely low HP coupled with extremely low effectiveness, I've always hated the "it'll just got KO'd next turn" argument. If the only resource you use is a Roseanne's Research to get Relicanth + Fighting and one-shot a Luxray X, then the Relicanth has served it's purpose, and it's even better if your opponent wants to burn resources to KO it instead of something more important, while at the same time having to try and get their Luxray back via NM/Aaron's.
