This Nidoking is one of the elite, secret subset of the Skyridge and Aquapolis sets known as the Crystal Pokémon. These cards are extremely hard to come by, and are easily the rarest cards in the two sets.
Due to an error, the types of colored Energy mentioned in the Crystal Type Poké-BODY do not correlate exactly to the types of colored Energy in the attacks. and match, but appears only in the Poké-BODY and appears only in the Rolling Thunder attack. It was ruled to play the power as if the were actually a to keep the power in line with the attack.