Well, those wealthy enough to afford them. His father, Gareth, was the gym leader at Rosethorn Gym, and had made a considerable amount of money from his life as a Pokemon trainer before settling down to run the gym.
Although Paul loved his father, he had no real like for his training methods, which were rather intense.
Train, train and train more, until you couldn't train anymore. Preferring to raise Pokemon with kindness and care, Paul had never really earned the respect of his father as a trainer.
