Straight from Stadium2, all the info to find which POKéMON you want in POKéMON Yellow.
Bulbasaur
Gotten from a girl in Cerulean City.
Level 10
One per game.
Ivysaur
Evolved from a Bulbasaur.
Venusaur
Evolved from an Ivysaur.
Charmander
Gotten from a boy on Route 24.
Level 10
One per game.
Charmeleon
Evolved from a Charmander.
Charizard
Evolved from a Charmeleon.
Squirtle
Gotten from an officer in Vermilion City.
Level 10
One per game.
Wartortle
Evolved from a Squirtle.
Blastoise
Evolved from a Wartortle.
Caterpie
Viridian Forest
Level 3 to 6
Often
Metapod
Viridian Forest
Level 4 to 6
Usually
Butterfree
Evolved from a Metapod.
Weedle
None
Kakuna
None
Beedrill
Evolved from a Kakuna.
Pidgey
Route 1
Level 2 to 7
Often
Route 2
Level 3 to 7
Often
Viridian Forest
Level 4 to 8
Usually
Route 5 and 6
Level 15 to 17
Usually
Route 7 and 8
Level 20 to 22
Usually
Route 11
Level 16 to 18
Usually
Route 12
Level 28
Sometimes
Route 13
Level 28
Not Often
Route 21
Level 11 to 17
Often
Route 24 and 25
Level 13 to 17
Usually
Pidgeotto
Viridian Forest
Level 9
Maybe
Route 5 and 6
Level 17
Rarely
Route 7 and 8
Level 24
Not Often
Route 11
Level 18 to 20
Not Often
Route 12
Level 28
Not Often
Route 13
Level 28
Sometimes
Route 14
Level 30
Not Often
Route 15
Level 32
Not Often
Route 21
Level 15 to 19
Not Often
Pidgeot
Evolved from a Pidgeotto.
Rattata
Route 1
Level 2 to 4
Usually
Route 2
Level 3 to 4
Usually
Route 3 and 4
Level 10 to 12
Sometimes
Route 5 and 6
Level 14 to 16
Usually
Route 7 and 8
Level 20
Sometimes
Route 9 and 10
Level 18
Sometimes
Route 11
Level 15 to 17
Usually
Route 16 and 18
Level 23 to 24
Usually
POKéMON Mansion
1F
Level 34 to 37
Usually
2F
Level 37 to 40
Usually
3F
Level 40 to 42
Usually
Route 21
Level 13 to 15
Usually
Route 22
Level 3
Not Often
Raticate
Route 9 and 10
Level 20
Rarely
Route 11
Level 17
Maybe
Route 16 and 18
Level 25 to 26
Rarely
POKéMON Mansion
1F
Level 34 to 37
Usually
2F
Level 37 to 40
Usually
3F
Level 40 to 43
Usually
B1F
Level 37 to 46
Usually
Route 21
Level 15
Rarely
Spearow
Route 3 and 4
Level 8 to 12
Often
Route 9
Level 17
Not Often
Route 16 and 18
Level 22 to 23
Usually
Route 22
Level 2 to 6
Not Often
Fearow
Route 9
Level 19
Maybe
Route 16 and 18
Level 24
Rarely
Route 17
Level 27 to 29
Usually
Route 23
Level 40 to 45
Sometimes
Ekans
None
Arbok
None
Pikachu
Gotten from Prof. Oak
Level 5
One per game.
Raichu
Evolved from Pikachu with a Thunderstone.
Sandshrew
Route 3 and 4
Level 8 to 10
Sometimes
Mt. Moon
1F
Level 12
Rarely
Sandslash
Cerulean Cave
2F
Level 56
Not Often
1F
Level 52
Not Often
Nidoran(f)
Route 2
Level 4 to 6
Sometimes
Route 9
Level 16 to 18
Usually
Route 10
Level 17
Not Often
Safari Zone
Center Area
Level 36
Sometimes
Area 1
Level 29
Sometimes
Area 2
Level 14
Sometimes
Area 3
Level 21
Sometimes
Route 22
Level 2 to 4
Usually
Nidorina
Route 9
Level 18
Rarely
Safari Zone
Area 1
Level 32
Not Often
Area 2
Level 23
Not Often
Route 23
Level 41 to 44
Usually
Nidoqueen
Evolved from a Nidorina with a Moon Stone.
Nidoran(m)
Route 2
Level 4 to 6
Sometimes
Route 9
Level 16 to 18
Usually
Route 10
Level 17
Not Often
Safari Zone
Center Area
Level 14
Sometimes
Area 1
Level 21
Sometimes
Area 2
Level 36
Sometimes
Area 3
Level 29
Sometimes
Route 22
Level 2 to 4
Usually
Nidorino
Route 9
Level 18
Rarely
Safari Zone
Center Area
Level 23
Not Often
Area 3
Level 32
Not Often
Route 23
Level 41 to 44
Usually
Nidoking
Evolved from a Nidorino with a Moon Stone.
Clefairy
Mt. Moon
1F
Level 11
Maybe
B1F
Level 10 to 12
Rarely
B2F
Level 9 to 13
Not Often
Clefable
Evolved from a Clefairy with a Moon Stone.
Vulpix
Celadon City Game Corner (1000 coins needed)
Level 18
Ninetails
Evolved from a Vulpix with a Fire Stone.
Jigglypuff
Route 5 and 6
Level 3 to 7
Not Often
Route 7 and 8
Level 19 to 24
Not Often
Wigglytuff
Celadon City Game Corner (2680 coins needed)
Level 22
Zubat
Mt. Moon
1F
Level 6 to 11
Often
B1F
Level 8 to 11
Often
B2F
Level 10 to 13
Often
Rock Tunnel
B1F
Level 15 to 21
Often
B2F
Level 20 to 22
Usually
Seafoam Islands
1F
Level 9 to 36
Often
B1F
Level 18 to 36
Usually
B2F and B3F
Level 27 to 36
Usually
B4F
Level 36 to 45
Usually
Victory Road
1F
Level 39 to 44
Sometimes
2F
Level 44
Not Often
Golbat
Seafoam Islands
1F
Level 27 to 36
Rarely
B1F
Level 27
Not Often
B2F
Level 27 to 36
Sometimes
B3F
Level 27
Sometimes
B4F
Level 27 to 36
Usually
Victory Road
2F
Level 39
Not Often
3F
Level 44
Sometimes
Cerulean Cave
1F
Level 50 to 55
Usually
2F
Level 52 to 57
Usually
B1F
Level 54 to 59
Usually
Oddish
Route 12 and 13
Level 25 to 27
Usually
Route 14 and 15
Level 26 to 28
Usually
Route 24 and 25
Level 12 to 14
Usually
Gloom
Route 12 and 13
Level 29
Rarely
Route 14 and 15
Level 30
Rarely
Cerulean Cave
1F
Level 55
Not Often
2F
Level 58
Rarely
Vileplume
Evolved from a Gloom with a Leaf Stone.
Paras
Mt. Moon
B1F
Level 9 to 11
Not Often
B2F
Level 13
Sometimes
Safari Zone
Center Area
Level 27
Rarely
Parasect
Safari Zone
Center Area
Level 27 to 32
Sometimes
Cerulean Cave
1F
Level 54
Rarely
Venonat
Route 14 and 15
Level 24 to 27
Sometimes
Route 24 and 25
Level 13 to 16
Not Often
Venomoth
Route 14 and 15
Level 30
Maybe
Cerulean Cave
1F
Level 54
Rarely
Diglett
Diglett's Cave
Level 15 to 22
Abundant
Dugtrio
Diglett's Cave
Level 29 to 31
Rarely
Meowth
None available in-game.
Persian
Evolved from a Meowth.
Psyduck
Route 6
Surfing
Level 15
Abundant
Golduck
Route 6
Level 15 to 20
Rarely
Mankey
Route 3 and 4
Level 9
Sometimes
Route 22
Level 3 to 5
Sometimes
Route 23
Level 36 to 41
Sometimes
Primeape
Route 23
Level 41 to 46
Rarely
Growlithe
POKéMON Mansion
1F
Level 26 to 38
Sometimes
Arcanine
Evolved from a Growlithe with a Fire Stone.
Poliwag
Pallet Town, Cerulean City, Vermilion City, S.S. Anne, Celadon City, Fuchsia City, Safari Zone, Seafoam Islands B3F, B4F, Cinnabar Town, Cerulean Cave, Route 6, 10, 11, 12, 13, 17, 18, 19, 20, 21, 24, and 25
Good Rod
Level 10
Often
Viridian City
Good Rod
Level 10
Often
Super Rod
Level 5 to 15
Always
Route 22
Good Rod
Level 10
Often
Super Rod
Leve 5 to 15
Abundant
Route 23
Good Rod
Level 10
Often
Super Rod
Level 25 to 30
Often
Poliwhirl
Route 22
Super Rod
Level 15
Not Often
Route 23
Super Rod
Level 30 to 40
Usually
Poliwrath
Evolved Poliwhirl with a Water Stone.
Abra
Route 5 and 6
Level 7
Sometimes
Route 7
Level 15 to 26
Usually
Route 8
Level 15 to 19
Sometimes
Celadon City Game Corner (230 coins needed)
Level 15
Kadabra
Route 8
Level 20 to 27
Rarely
Alakazam
Gotten through trading a Kadabra to/from any version.
Machop
Rock Tunnel
B1F
Level 17 to 21
Not Often
B2F
Level 18 to 20
Sometimes
Route 10
Level 16 to 18
Rarely
Machoke
Victory Road
2F
Level 39 to 42
Rarely
3F
Level 42 to 45
Not Often
Machamp
Gotten through trading a Machoke to/from any version.
Bellsprout
Route 12 and 13
Level 25 to 27
Usually
Route 14 and 15
Level 26 to 28
Usually
Route 24 and 25
Level 12 to 14
Usually
Weepinbell
Route 12 and 13
Level 29
Rarely
Route 14 and 15
Level 30
Rarely
Cerulean Cave
1F
Level 55
Not Often
2F
Level 58
Rarely
Victreebel
Evolved from a Weepinbell with a Leaf Stone
Tentacool
Pallet Town
Super Rod
Level 10 to 20
Usually
Vermilion City and Route 11
Super Rod
Level 10 to 20
Abundant
S.S. Anne
Super Rod
Level 10 to 15
Often
Route 13
Super Rod
Level 10
Sometimes
Route 17
Super Rod
Level 5 to 15
Often
Route 18
Super Rod
Level 15
Usually
Route 19 and 21
Surfing
Level 5 to 40
Always
Super Rod
Level 15 to 30
Often
Seafoam Islands
B3F and B4F
Surfing
Level 20 to 40
Often
Route 20
Surfing
Level 5 to 40
Always
Super Rod
Level 20
Usually
Cinnibar Island
Super Rod
Level 15 to 30
Usually
Tentacruel
Route 19 and 21
Super Rod
Level 30
Not Often
Route 20
Super Rod
Level 20 to 40
Usually
Geodude
Mt. Moon
1F
Level 10
Sometimes
B1F
Level 10 to 11
Sometimes
B2F
Level 11
Sometimes
Rock Tunnel
B1F
Level 16 to 20
Usually
B2F
Level 17 to 21
Usually
Victory Road
1F
Level 26 to 41
Often
2F
Level 31 to 41
Often
3F
Level 36 to 46
Often
Graveler
Victory Road
1F
Level 41 to 47
Rarely
2F
Level 44
Not Often
3F
Level 41 to 47
Sometimes
Cerulean Cave
1F
Level 45
Sometimes
2F
Level 50
Sometimes
B1F
Level 55
Sometimes
Golem
Gotten through trading a Graveler to/from any version.
Ponyta
Route 17
Level 28 to 32
Usually
Rapidash
Evolved from a Ponyta.
Slowpoke
Route 12 and 13
Surfing
Level 15
Abundant
Seafoam Islands
1F
Level 28 to 30
Sometimes
B1F
Level 29
Not Often
B2F
Level 31
Rarely
Slowbro
Route 12 and 13
Surfing
Level 15 to 20
Rarely
Seafoam Islands
B2F
Level 31
Maybe
Magnemite
Route 10
Level 16 to 22
Often
Power Plant
Level 30 to 35
Usually
Magneton
Power Plant
Level 33 to 38
Sometimes
Farfetch'd
Route 12 and 13
Level 26 to 31
Rarely
Doduo
Route 16 and 18
Level 22 to 26
Usually
Route 17
Level 26 to 28
Often
Dodrio
Route 27
Level 29
Maybe
Seel
Seafoam Islands
B1F
Level 22 to 26
Rarely
B2F
Level 24
Not Often
B3F
Level 26 to 30
Sometimes
B4F
Level 28 to 32
Sometimes
Dewgong
Seafoam Islands
B3F
Level 28 to 32
Rarely
B4F
Level 30 to 34
Rarely
Grimer
Power Plant
Level 33 to 37
Sometimes
POKéMON Mansion
1F
Level 23 to 26
Sometimes
2F
Level 26 to 35
Usually
3F
Level 32 to 38
Usually
B1F
Level 35 to 38
Usually
Muk
Power Plant
Level 33 to 37
Rarely
POKéMON Mansion
2F
Level 35 to 38
Rarely
3F
Level 38 to 41
Rarely
B1F
Level 41
Not Often
Shellder
S.S. Anne
Super Rod
Level 10
Not Often
Route 17
Super Rod
Level 25 to 35
Usually
Route 18
Super Rod
Level 20 to 40
Often
Cloyster
Evolved from a Shellder with a Water Stone.
Ghastly
POKéMON Tower
3F and 4F
Level 18 to 25
Abundant
5F and 6F
Level 21 to 27
Abundant
7F
Level 23 to 29
Abundant
Haunter
POKéMON Tower
3F and 4F
Level 20 to 25
Rarely
5F and 6F
Level 22 to 27
Rarely
7F
Level 24 to 29
Rarely
Gengar
Gotten through trading a Haunter to/from any version.
Onix
Rock Tunnel
B2F
Level 14 to 22
Not Often
Victory Road
1F
Level 43 to 45
Not Often
2F
Level 45 to 47
Not Often
3F
Level 49
Not Often
Drowzee
Route 11
Level 15 to 19
Usually
Hypno
Evolved from a Drowzee.
Krabby
Route 10
Super Rod
Level 15 to 20
Often
Seafoam Islands
1F
Level 25 to 27
Usually
B1F
Level 26 to 28
Usually
B2F
Level 27 to 29
Usually
B3F
Level 29 to 31
Sometimes
Super Rod
Level 25
Usually
B4F
Level 30
Sometimes
Super Rod
Level 25
Usually
Route 25
Level 10 to 15
Often
Kingler
Route 10
Super Rod
Level 25
Not Often
Seafoam Islands
Level 28
Rarely
B2F
Level 28
Not Often
B3F
Level 30
Not Often
Super Rod
Level 35
Sometimes
B4F
Level 32
Not Often
Super Rod
Level 35
Sometimes
Route 25
Level 15 to 25
Usually
Voltorb
Power Plant
Level 33 to 37
Sometimes
Electrode
Evolved from a Voltorb.
Exeggcute
Safari Zone
Center Area
Level 24
Sometimes
Area 1 and 3
Level 22 to 26
Sometimes
Area 2
Level 20
Sometimes
Exeggutor
Evolvled from an Exeggcute with a Leaf Stone.
Cubone
POKéMON Tower
5F
Level 20
Rarely
6F
Level 22
Rarely
7F
Level 24
Rarely
Safari Zone
Area 1 and 3
Level 19
Not Often
Area 2
Level 16
Rarely
Marowak
Safari Zone
Area 1 and 3
Level 24
Rarely
Hitmonlee
Gotten from the fighting gym master.
Level 20
One per game.
Hitmonchan
Gotten from the fighting gym master.
Level 20
One per game.
Lickitung
Cerulean Cave
B1F
Level 50 to 55
Rarely
Koffing
None available in-game.
Weezing
Evolved from Koffing.
Rhyhorn
Safari Zone
Center Area
Level 20
Not Often
Area 2
Level 25
Not Often
Cerulean Cave
2F
Level 50
Not Often
B1F
Level 52
Not Often
Rhydon
Cerulean Cave
2F
Level 58 to 60
Rarely
B1F
Level 62
Not Often
Chansey
Safari Zone
Center Area
Level 7
Maybe
Area 1
Level 21
Rarely
Cerulean Cave
B1F
Level 56
Rarely
Tangela
Safari Zone
Center Area
Level 22
Rarely
Area 3
Level 27
Maybe
Kangaskhan
Safari Zone
Area 2
Level 28 to 33
Sometimes
Horsea
Vermilion City and Route 11
Super Rod
Level 5
Not Often
Route 10
Super Rod
Level 10
Sometimes
Route 12
Super Rod
Level 20 to 25
Often
Route 13
Level 15 to 20
Often
Seadra
Route 12
Super Rod
Level 25 to 35
Usually
Route 13
Super Rod
Level 20
Not Often
Goldeen
Pallet Town, Viridian City, Vermilion City, S.S. Anne, Fuchsia City, Safari Zone, Seafoam Islands B3F and B4F, Cinnibar Island, Route 10, 11, 12, 13, 17, 18, 19, 20, 21, 22, 23, and 25
Good Rod
Level 10
Often
Cerulean City
Good Rod
Level 10
Often
Super Rod
Level 25 to 30
Often
Celadon City and Route 6
Good Rod
Level 10
Often
Super Rod
Level 5 to 20
Always
Route 24
Good Rod
Level 10
Often
Super Rod
Level 20 to 30
Abundant
Cerulean Cave
1F
Good Rod
Level 10
Often
Super Rod
Level 25
Usually
B1F
Good Rod
Level 10
Often
Super Rod
Level 30
Usually
Seaking
Cerulean City
Super Rod
Level 30 to 40
Usually
Route 24
Super Rod
Level 30
Not Often
Cerulean Cave
1F
Super Rod
Level 35 to 55
Often
B1F
Level 40 to 60
Often
Staryu
Pallet Town
Super Rod
Level 5 to 10
Often
S.S. Anne
Super Rod
Level 15
Sometimes
Route 19 and 21
Super Rod
Level 20
Usually
Seafoam Islands
B3F and B4F
Surfing
Level 30
Usually
Super Rod
Level 20 to 40
Usually
Route 20
Super Rod
Level 30
Sometimes
Cinnibar Island
Super Rod
Level 10 to 15
Often
Starmie
Evolved from a Staryu with a Water Stone.
Mr. Mime
Gotten through an in-game trade.
Scyther
Celadon City Game Corner (6500 coins needed)
Level 30
Safari Zone
Area 1
Level 15
Maybe
Area 2
Level 25
Rarely
Jynx
Gotten through an in-game trade.
Electabuzz
Not available in-game.
Magmar
Not available in-game.
Pinsir
Celadon City Game Corner (6500 coins needed)
Level 30
Safari Zone
Area 2
Level 15
Maybe
Area 3
Level 25
Rarely
Tauros
Safari Zone
Area 1 and 3
Level 21
Not Often
Magikarp
Pallet Town, Viridian City, Cerulean City, Vermilion City, S.S. Anne, Celadon City, Seafoam Islands B3F and B4F, Cinnibar Island, Cerulean Cave, Route 6, 10, 11, 12, 13, 17, 18, 19, 20, 21, 22, 23, 24, and 25
Old Rod
Level 5
Always
Fuchsia City
Old Rod
Level 5
Always
Super Rod
Level 5 to 15
Abundant
Safari Zone
Center Area
Old Rod
Level 5
Always
Super Rod
Level 5 to 10
Often
Area 1, 2, and 3
Old Rod
Level 5
Always
Super Rod
Level 5 to 15
Abundant
Gyarados
Fuchsia City
Super Rod
Level 15
Not Often
Lapras
Gotten from a man in the Silph Co. building.
Level 15
One per game.
Ditto
POKéMON Mansion
B1F
Level 12 to 24
Not Often
Cerulean Cave
1F
Level 55 to 60
Rarely
2F
Level 60
Not Often
B1F
Level 60 to 65
Sometimes
Eevee
Gotten from a man in the Celadon Manison.
One per game.
Vaporeon
Evolved from an Eevee with a Water Stone.
Jolteon
Evolved from an Eevee with a Thunder Stone.
Flareon
Evolved from an Eevee with a Fire Stone.
Porygon
Celadon City Game Corner (9999 coins needed)
Level 26
Omanyte
Cinnibar Island Lab (Helix Fossil needed)
Level 30
One per game.
Omastar
Evolved from a Omanyte.
Kabuto
Cinnibar Island Lab (Dome Fossil needed)
Level 30
One per game.
Kabutops
Evolved from a Kabuto.
Aerodactyl
Cinnibar Island Lab (Old Amber needed)
Level 30
One per game.
Snorlax
Route 11
Level 30
Two per game.
Articuno
Seafoam Islands
B4F
Level 50
One per game.
Zapdos
Power Plant
Level 50
One per game.
Moltres
Victory Road
2F
Level 50
One per game.
Dratini
Safari Zone
Center Area
Super Rod
Level 10
Sometimes