Generation I (Game Boy)
1. Pokémon Red/Pokémon Green/Pokémon Blue (exactly the same game with different Pokemon = no bonus development time involved)
2. Pokémon Yellow (Slightly upgraded and added color scheme)
Generation II (Game Boy Color)
3. Pokémon Gold and Silver
4. Pokémon Crystal (Again, a sister game, but has minor fixes so let's treat it as a "new" one)
Generation III (Game Boy Advance)
5. Pokémon Ruby and Sapphire
6. Pokémon FireRed and LeafGreen
7. Pokémon Emerald (Another f-ing sister game, but at least has some changes, so let's call it a "new one" too)
Generation IV (Nintendo DS)
8. Pokémon Diamond and Pearl
9. Pokémon Platinum (Yet ANOTHER sister game. Whee...)
10. Pokémon HeartGold and SoulSilver
Generation V (Nintendo DS)
11. Pokémon Black and White
Misc. Games (no particular order)
12. Pokémon Trading Card Game
13. Pokemon Trading Card Game 2: Here Comes Team Rocket!
14. Pokemon Trading Card Game ONLINE
15. Pokemon Pinball
16. Pokemon Pinball: Ruby and Saphire
17. Pokémon Party Mini (Pokemon Mini)
18. Pokémon Zany Cards (Pokemon Mini)
19. Pokémon Pinball Mini (Pokemon Mini)
20. Pokémon Puzzle Collection (Pokemon Mini)
21. Pokémon Tetris Mini (Pokemon Mini)
22. Pokémon Breeder Mini (Pokemon Mini)
23. Pokémon Puzzle Collection Vol.2 (Pokemon Mini)
24. Pichu Bros. Mini (Pokemon Mini)
25. Pokémon Race Mini (Pokemon Mini)
26. Togepi's Adventure (Pokemon Mini)
27. Pokemon Battrio
28. Pokemon Stadium
29. Pokemon Snap!
30. Pokemon Stadium 2
31. Hey, you! Pikachu!
32. Pokemon Puzzle League
33. Pokemon Puzzle Challenge
34. Pokemon Colosseum
35. Pokemon XD: Gale of Darkness
36. Pokemon Channel
37. Pokemon Battle Revolution
38. Pokemon Rumble
39. My Pokemon Ranch
40. Pokemon Mystery Dungeon Light/Storm/Blazing Adventure
41. Pokepark Wii - Pikachu's Adventure
42. Pokémon Mystery Dungeon: Red & Blue Rescue Team
43. Pokémon Dash
44. Pokémon Trozei!
45. Pokémon Ranger
46. Pokémon Mystery Dungeon: Explorers of Time and Explorers of Darkness
47. Pokémon Ranger: Shadows of Almia
48. Pokémon Mystery Dungeon: Explorers of Sky
49. Pokémon Ranger: Guardian Signs
50. PokéPark: Fishing Rally DS
51. Pokemon Picross
52. Pokemon Typing DS
53. Catch the Numbers! (Sega Pico)
54. Advanced Generation: I've Begun Hiragana and Katakana! (Sega Pico)
55. Advanced Generation: Pico for Everyone Pokémon Loud Battle! (Sega Pico)
56. Advanced Generation: Pokémon Number Battle! (Advanced Pico)
57. Intellectual Training Drill Diamond & Pearl: Letter and Number Intelligence Game (Advanced Pico)
58. Diamond & Pearl: Search for Pokémon! Adventure in the Maze! (Advanced Pico)
59. Best Wishes: Intelligence Training Pokémon Big Sports Meet! (Advanced Pico)
60. Team Rocket Blast Off (PC)
61. Poké Ball Launcher (PC)
62. Seek & Find (PC)
63. Project Studio Red and Blue (PC)
64. Pokémon Play It!
65. Pokémon Play It! v2
66. PokéROM
67. Pokemon Masters Arena
68. Pokemon PC Master
69. Pokémate
70. Pokemon Pikachu (Handheld)
71. Pokemon Pikachu 2 (Handheld)
72. Cyber Poké Ball (Handheld)
73. Cyber Pokédex (Handheld)
74. Digital Poké Ball D & P
75. PokeWalker (free with HG/SS, but no matter how you look at it, it's a separate "game")
76. Pokémon Box Ruby & Sapphire (Not really a "game" as such, it just stores Pokemon)
77. Pokémon Stadium 0 (Pokemon Stadium JAP)
+ Mobile Games I DON'T feel like counting at the moment. I'm not even sure if there are any "official" ones other than Pokemate.
Fix'd your slight miscalculation.
Honest opinion? I'm all for keeping franchises alive, but please, don't force-milk them. Take some time before releasing a new game, Gamefreak. Release a game that FOR ONCE has decent upgrades, not just cosmetic ones.