Occasionally, a trainer competes in the Pokemon League who has not fully evolved all their pokemon. Perhaps it is the weak sister of the team and evolves late, perhaps, like Yellow, they prefer their pokemon's earlier forms, or perhaps the pokemon themselves wish not to evolve. Typically, they are eliminated in the first or second round: evolution provides most pokemon with such a great boost in ability that no amount of training or tactical acumen can compensate.
The one notable exception to this rule was Bruno (now of the Elite Four) who as a younger trainer used a Nidorino alongside his powerful Steelix, Hitmonlee, Hitmonchan, and Machamp. In the first couple matches of the tournament, he used his Nidorino last, and managed to catch his opponents underestimating him; in the higher rounds, he used it first and still no one could stand up to it. The finals saw a sleeping Nidorino sent out against Agatha's Gengar; its dreams were eaten, then it woke up, jumped onto the ghost and bit it so hard it was said that it stole its dreams back. Bruno was champion.
He would later be defeated by a dragon trainer named Lance, but would not use his Nidorino in that battle. Some say that, unable to control it after his loss, he released it into Victory Road. They go on to claim that it tracks down and takes on worthy trainers and even once defeated Moltres. If the stories are to be believed, the Nidorino was traumatized by the Gengar's attack and seeks a new trainer, one who can control its hatred of ghosts and allow it a good night's sleep once again.