Ash has obtained Pikachu, Caterpie, Metapod, Butterfree, Pidgeotto, Pidgeot, Charmander, Charmeleon, Charizard, Bulbasaur, Squirtle, Primeape, Haunter, Krabby, Kingler, Lapras, Muk, Tauros, Snorlax, Heracross, Totodile, Chikorita, Bayleef, Cyndaquil, Quilava, Noctowl, Torkoal, Treecko, Grovyle, Sceptile, Glalie, Tailow, Swellow, Phanpy, Donphan, Larvitar, Gible, Gligar, Gliscor, Buizel, Starly, Staravia, Staraptor, Chimchar, Monferno, Infernape, Turtwig, Grotle, Torterra, Sandile, Krokorok, Krookodile, Roggenrola, Boldore, Sewaddle, Swadloon, Leavanny, Tympole, Palpitoad, Scraggy, Snivy, Pidove, Tranquil, Unfezant, Tepig, Pignite, Oshawott, Froakie, Frogadier, Greninja, Fletchling, Fletchinder, Talonflame, Noibat, Noivern, Goomy, Sliggoo, Goodra, Aipom, Snorunt and Beedrill.
So, in total, if I counted correctly, Ash has obtained 81 Pokemon.
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