The first two seasons of Pokémon only featured the first 150 fictional creatures.
Season 1: Indigo League
1. Pokémon: I Choose You!
- Debuts: Pidgey (#16), Rattata (#19), Spearow (#21), Pikachu (#25), Nidorino (#33), Gengar (#94), Onix (#95)
2. Pokémon Emergency!
- Debuts: Caterpie (#10), Ekans (#23), Meowth (#52), Koffing (#109), Chansey (#113), Goldeen (#118)
- Team Rocket first appears in this episode. Misty follows Ash in his Pokémon journey after he ruins her bike.
3. Ash Catches a Pokémon
- Debuts: Metapod (#11), Pidgeotto (#17)
4. Challenge of the Samurai
- Debuts: Butterfree (#12), Weedle (#13), Kakuna (#14), Beedrill (#15), Pinsir (#127)
5. Showdown in Pewter City
- Debuts: Geodude (#74)
- Ash earns a Boulder Badge from Pewter City in this episode. In addition, Brock joins Ash and Misty in their Pokémon journey.
6. Clefairy and the Moon Stone
- Debuts: Sandshrew (#27), Clefairy (#35), Clefable (#36), Zubat (#41), Paras (#46), Staryu (#120)
7. The Water Flowers of Cerulean City
- Debuts: Seel (#86), Starmie (#121)
- Ash earns a Cascade Badge from the Cerulean City gym in this episode.
8. The Path to the Pokémon League
- In this episode, we see a Pokémon trainer who has never been defeated, and owns a gym that was not licensed by the Pokémon League. This is also the first episode where no new Pokémon make any debuts.
9. The School of Hard Knocks
- Debuts: Pidgeot (#18), Weepinbell (#70), Graveler (#75), Cubone (#104)
10. Bulbasaur and the Hidden Village
- Debuts: Bulbasaur (#1), Oddish (#43), Magikarp (#129)
11. Charmander - The Stray Pokémon
- Debuts: Charmander (#4)
12. Here Comes the Squirtle Squad
- Debuts: Squirtle (#7)
13. Mystery at the Lighthouse
- Debuts: Krabby (#98), Dragonite (#149)
14. Electric Shock Showdown
- Debuts: Raichu (#26)
- Ash wins a Thunder Badge from Lt. Surge at Vermilion City Gym in this episode.
15. Battle Aboard the S.S. Anne
- Debuts: Raticate (#20), Persian (#53)
16. Pokémon Shipwreck
- Debuts: Gyarados (#130)
17. Island of the Giant Pokémon
- Debuts: Slowpoke (#79), Slowbro (#80)
18. Tentacool & Tentacruel
- Debuts: Tentacool (#72), Tentacruel (#73), Horsea (#116)
19. The Ghost of Maiden's Peak
- Debuts: Venusaur (#3), Blastoise (#9), Gastly (#92)
20. Bye Bye Butterfree
- This episode features a pink Butterfree, and marks the last appearance of Ash's Butterfree. He now only has five Pokémon left.
21. Abra and the Psychic Showdown
- Debuts: Abra (#63), Kadabra (#64)
22. The Tower of Terror
- Debuts: Haunter (#93)
- Ash catches a Haunter in this episode.
23. Haunter vs. Kadabra
- Ash wins his fourth badge, the Marsh Badge, from the Saffron City Gym, in this episode. His Haunter now belongs to Sabrina, the gym leader.
24. Primeape Goes Bananas
- Debuts: Mankey (#56), Primeape (#57), Poliwag (#60), Poliwhirl (#61), Bellsprout (#69), Dodrio (#85)
- Ash catches a Primeape in this episode.
25. Pokémon Scent-sation!
- Debuts: Gloom (#44), Vileplume (#45), Victreebel (#71), Grimer (#88), Exeggcute (#102), Tangela (#114)
- Ash wins a Rainbow Badge (his fifth badge) from the Celadon City Gym.
26. Hypno's Naptime
- Debuts: Psyduck (#54), Drowzee (#96), Hypno (#97)
27. Pokémon Fashion Flash
- Debuts: Male Nidoran (#32), Vulpix (#37), Venonat (#48)
28. The Punchy Pokémon
- Debuts: Poliwrath (#62), Machop (#66), Machoke (#67), Machamp (#68), Hitmonlee (#106), Hitmonchan (#107)
29. Sparks Fly for Magnemite
- Debuts: Fearow (#22), Female Nidoran (#29), Growlithe (#58), Magnemite (#81), Magneton (#82), Muk (#89)
30. Dig Those Diglett!
- Debuts: Arbok (#24), Diglett (#50), Dugtrio (#51), Weezing (#110)
31. The Ninja Poké-Showdown
- Debuts: Golbat (#42), Venomoth (#49), Voltorb (#100)
- Ash wins a Soul Badge in this episode at the Fuchsia Gym.
32. The Flame Pokémon-athon!
- Debuts: Sandslash (#28), Nidorina (#30), Ponyta (#77), Rapidash (#78), Electrode (#101), Rhyhorn (#111), Tauros (#128)
33. The Kangaskhan Kid
- Debuts: Kangaskhan (#115)
34. The Bridge Bike Gang
- Debuts: Golem (#76), Shellder (#90), Cloyster (#91)
35. Ditto's Mysterious Mansion
- Debuts: Ditto (#132), Dratini (#147)
36. Pikachu's Goodbye
- In this episode, Ash attempts to release Pikachu into the wild, but Pikachu returns to him.
37. The Battling Eevee Brothers
- Debuts: Ninetales (#38), Exeggutor (#103), Eevee (#133), Vaporeon (#134), Jolteon (#135), Flareon (#136)
38. Wake Up Snorlax!
- Debuts: Snorlax (#143)
39. Snowdown at Dark City
- Debuts: Kingler (#99), Rhydon (#112), Scyther (#123), Electabuzz (#125)
40. The March of Exeggutor Squad
- Debuts: Charmeleon (#5)
41. The Problem with Paras
- Debuts: Parasect (#47)
42. The Song of Jigglypuff
- Debuts: Jigglypuff (#39)
43. Attack of the Prehistoric Pokémon
- Debuts: Charizard (#6), Omanyte (#138), Omastar (#139), Kabuto (#140), Kabutops (#141), Aerodactyl (#142)
44. A Chansey Operation
- Debuts: Ivysaur (#2), Nidoking (#34), Porygon (#137)
45. Holy Matrimony!
- In a flashback of James's childhood, it is revealed that he once owned a Growlithe, nicknamed "Growlie".
46. So Near, Yet So Farfetch'd
- Debuts: Farfetch'd (#83)
47. Who Gets to Keep Togepi?
- Togepi, first appearing in this episode, is not any of the first 151 Pokémon. Instead, it is #175, and therefore makes its video game debut with Pokémon Gold and Silver.
48. Bulbasaur's Mysterious Garden
- Ash's Bulbasaur refuses to evlove in this episode.
49. Princess vs. Princess
- Debuts: Lickitung (#108)
50. The Purr-fect Hero
51. The Case of the K-9 Caper!
52. Pokémon Paparazzi
53. The Ultimate Test
54. The Breeding Center Secret
55. Riddle Me This
- Debuts: Magmar (#126)
56. Volcanic Panic
- Ash wins a Volcano Badge in this episode.
57. Beach Blank-Out Blastoise
- Debuts: Wartortle (#8)
58. The Misty Mermaid
- Debuts: Dewgong (#87), Seaking (#119)
59. Clefairy Tales
60. The Battle of the Badge
- Debuts: Nidoking (#34), Arcanine (#59), Mewtwo (#150)
- Ash wins the Earth Badge at the Viridian City Gym, earning his ticket to the Pokémon League.
61. It's Mr. Mime Time
- Debuts: Mr. Mime (#122)
- Ash's mother, Delia, owns a Mr. Mime in this episode, nicknamed "Mimey".
62. Holiday Hi-Jynx
- Debuts: Jynx (#124), Lapras (#131)
63. Snow Way Out
- This episode takes place before Episode 40, as Ash's Charmander is featured here.
64. Showdown at the Po-ké Corral
- Debuts: Doduo (#84)
65. The Evolution Solution
66. The Pi-Kahuna
67. Make Room for Gloom
68. Lights, Camera, Quack-tion
- Debuts: Wigglytuff (#40)
69. Go West Young Meowth
- Meowzie, a female Meowth given this nickname, appears in this episode.
70. To Master the Onixpected!
71. The Ancient Puzzle of Pokémopolis
- Debuts: Alakazam (#65)
72. Bad to the Bone
- Debuts: Marowak (#105)
73. All Fired Up!
- Debuts: Moltres (#146)
74. Round One - Begin!
- Debuts: Seadra (#117)
75. Fire and Ice
76. The Fourth Round Rumble
77. A Friend in Deed
78. Friend and Foe Alike
79. Friends to the End
- This episode marks the end of the Indigo League.
- The four Pokémon that did not appear within these 79 episodes were Golduck (#55), Articuno (#144), Zapdos (#145), and Dragonair (#148). Golduck first appeared in Pokémon: The First Movie (premiered in theaters 15 days before the last episode of the Indigo League), while Articuno and Zapdos first appeared in Pokémon: The Movie 2000 (premiered on July 21, 2000), and Dragonair made its debut in one of the three banned episodes (The Legend of Dratini). In the United States, it first appeared in a Master Quest episode, Dueling Heroes, in 2002.
Season 2: Orange Islands
80. Pallet Party Panic
81. A Scare in the Air
82. Pokéball Peril
83. The Lost Lapras
84. Fit to be Tide
85. Pikachu Re-Volts
86. The Crystal Onix
87. In the Pink
88. Shell Shock
89. Stage Fight
90. Bye Bye Psyduck
91. The Joy of Pokémon
92. Navel Maneuvers
93. Snack Attack
94. A Shipful of Shivers
95. Meowth Rules!
96. Tracey Gets Bugged
97. A Way Off Day Off
98. The Mandarin Island Miss-Match
99. Wherefore Art Thou, Pokémon?
100. Get Along, Little Pokémon
101. The Mystery Menace
102. Misty Meets Her Match
103. Bound for Trouble
104. Charizard Chills
105. The Pokémon Water War
106. Pokémon Food Fight
107. Pokémon Double Trouble
108. The Wacky Watcher
109. The Stun Spore Detour
110. Hello Pummelo
111. Enter the Dragonite
112. Viva Las Lapras
113. The Underground Round Up
114. A Tent Situation
115. The Rivalry Revival
Near the beginning of this season, Brock leaves the group and Tracey takes his place. Then at the end of this season, Tracey leaves the group again after deciding to stay in Pallet Town and become Oak's assistant. Brock rejoins the group, and our heroes are off to a completely new Pokémon journey.