Instructions
Walk in the grassy areas on Route 35 for a 30 percent chance of encountering a wild male Nidoran. Route 35 is north of Goldenrod City, where Pokemon trainers collect their third Gym Badge, making it a location found early in "Pokemon SoulSilver."
Capture a male Nidoran in a Poke Ball. Male Nidoran are purple and walk on four legs, while female Nidoran are blue and are often seen standing on their back legs.
Train your male Nidoran to level 16 to evolve it into Nidorino. Nidorino is the middle evolutionary step between a male Nidoran and Nidoking. Nidorino are strong and aggressive Poison-type monsters that are much larger than Nidoran.
Expose Nidorino to a Moon Stone item, and it will evolve into Nidoking. You can find Moon Stones in two areas near the start of "Pokemon SoulSilver." Win a Bug Catching Contest, located at the north end of Route 35, for a chance to win a Moon Stone if you take first place. There is a second Moon Stone located in the southeast room inside the Ruins of Alph. You can find it by lighting the dark chamber by using the Pokemon move Flash.