All it learns is Splash, Teleport, and Cosmic Power. Is it even useful?
No, they really aren't useful at all in any standard competitive formats.
However, in Hackmons, Cosmoem can be a beast. 131 Def and SpD with eviolite access? Are you serious? It sees some good use when you're allowed to have illegal movesets and abilities, but other than that, it really just has nothing to work with.