He has 30 altogether. But they are all at Professor's Lab and he has only used one of the thirty for battle.
Ash spent some time in the Safari Zone in the episode EP035. He was
attempting to catch as many Pokémon as possible, though all he ended
up with were thirty Tauros as they always ran in front of his Safari
Balls when he tried to make a catch. At the end of Ash's adventures in
the Safari Zone, all thirty Tauros were sent to Professor Oak's
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