Here is a list / summary of the major events which took place in the first season:
Ash earns Pikachu's trust and gains 2 travelling companions - Misty (from the Cerulean City Gym) and Brock (Pewter City Gym).
Team Rocket starts trying to capture Pikachu
Ash catches a Caterpie
Ash catches a Pidgeotto
Caterpie evolves into Metapod
Metapod evolves into Butterfree
Ash beats Brock in Pewter City Gym on second attempt. Brock joins Ash's journey. Ash get Boulder Badge
Brock catches Zubat
Ash gets to Cerulean City. He beats Misty in a battle. Ash gets Cascade Badge
Ash catches Bulbasaur
Ash catches Charmander
Ash catches Squirtle
Ash catches a Krabby
Ash beats Lt. Surge on second attempt in Vermillion City Gym. He gets Thunder Badge
Ash trades Butterfree for a Raticate and back again
Misty catches Horsea
Ash releases Butterfree
Ash finds Gym Leader Sabrina. Loses to her the first time round.
Ash catches a Haunter in Lavender Town
Ash gets to Sabrina and beats her in the Saffron City Gym. Ash gets Marsh Badge
Ash gives Haunter to Sabrina
Ash catches a Primeape
Ash beats Erika in Celadon Gym and gets Rainbow Badge
Brock catches Vulpix
Ash gives Primeape away
Ash catches a Muk
Jessie and James evolve their Ekans and Koffing into Arbok and Weeziing
Ash beats Koga in Fuschia Gym. He gets the Soul Badge
Misty catches Psyduck
Ash catches 30 Tauros (not seen in US)
Ash tries to release Pikachu, but fails
Charmander evolves into Charmeleon
Jigglypuff starts to follow the gang
Ash encounters all 5 extinct Pokemon
Charmeleon evolves into Charizard
Ash finds a Togepi egg
We find out that James used to have a Growlithe companion
Togepi hatches. Ash, Misty, and Brock have a tournament. Ash wins, but Togepi goes to Misty
Bulbasaur holds back his evolution
Jessie catches a Likitung
Todd joins the gang
Todd leaves the gang
James' Weepinbell evolves into Victreebell
Ash beats Blaine on second attempt with Charizard in the Cinnibar Gym. Ash gets Volcano Badge
Misty gives her Starmie and Horsea to her sisters in Cerulean City
Giovanni employs Mewtwo
Giovanni tests out his strongest Pokemon (Mewtwo) against Gary Oak
Ash beats Team Rocket in the Viridian Gym. Ash gets the Earth Badge
Ash's mom gets a Mr. Mime
Mewtwo breaks out of Giovanni's lab
Ash battles Mewtwo. Ash loses
Mewtwo makes clones of numerous Pokemon
Mewtwo forces all Pokemon to fight their clones.
Ash gets killed by stopping Mew and Mewtwo from fighting. The tears of all surrounding Pokemon bring him back to life.
Ash goes to the Pokemon League competitionand beats all 4 fields
Richie joins the group
Ash loses to Richie
Richie loses the competition as well
Ash comes in the top 16 in the Pokemon League
Richie leaves the group
Ash leaves to go to the Orange Islands to get the GS Ball from Professor Ivy
Pidgeotto evolves into Pidgeot
