Breed a female Rhyhorn with a male Pokémon of the following evolution lines that learn Curse via levelling up:
Slowpoke / Slowbro / Slowking
Numel / Camerupt
Torkoal
Turtwig / Grotle / Torterra
Bidoof / Bibarel
Bergmite / Avalugg
The result will be a baby Rhyhorn that knows Curse! For a complete list of compatible parents, look here.
