In rotation
Pikachu (starter)
pidove-Tranquill-Unfazant (first Unova pokemon)
Oshawott (originality owned by professor Juniper)
Tepig-Pignite (abandon by his trainer)
Snivey (unusual strong for a wild pokemon)
egg-Scraggy (egg hatchet)
sewaddle-Swadloon-Leavanny (evolved into Swadloon in a gym battle)
Palpitoad (leader of a group tympole)
roggenrola-Boldore (ash helped his roggenrola family)
(Sandile)-Krokorok (was first pikachu's rival)
At professor Oak's
Bulbasaur (refuses to evolve)
Krabby-Kingler (as a krabby he fought 3 pokemon in a row then he evolves)
Muk (is super friendly to everybody)
Tauros (x30)
Snorlax (caught at seven grapefruit island)
Heracross (is ash's first unique type combination)
Chikorita-Bayleef (is ash's only pokemon that evolved in the Johto series)
Cyndaquil-Quilava (needs 507 episodes to evolve)
Totodile (Is not captured in a regular poke ball)
Noctowl (Ash's first and only shiny pokemon)
egg-Phanpy-Donphan (egg hatched)
Taillow-Swallow (was the leader of a flock taillow)
Treecko-Grovyle-Sceptile (ash's first full evolved grass-type starter)
Corphish (Corphish is the only evolution-capable Pokémon Ash caught in Hoenn that did not
evolve)
Torkoal (sometimes acting like a crybaby)
Snorunt-Glalie (likes (as a sign of adoration) to freeze ash)
Starly-Staravia-Staraptor (it was actually caught to find pikachu)
Turtwig-Grotle-Torterra (as a turtwig he was the leader of a huge forest)
Chimchar-Monferno-Infernape (first belongs to Paul)
Buizel (was originality caught by Dawn but they make a trade with ash's Aipom)
Gible (The first dragon pokemon that is owned by a main character)
In training
Primeape (Is leave by another trainer to become a top-boxer)
Charmander-Charmeleon-Charizard (stay at the Characific Valley to be trained)
Squirtle (Member of the Squirtle-squat were it is training)
Gliscor (Is at the moment training with McCann the air-battle master)