RNG from one to 100. The number you get is the choice of Pokémon you can run into.

Rarity:
C: Common (1-50)
U: Uncommon (51-80)
*: Rare (81-95)
**: Super-rare (96-100)


Route 1: Basic trainer route
Levels are between 2 and 4 for all Pokemon
Rattata C
Bidoof C
Patrat C
Zigzagoon C
Sentret C
Pidgey C
Spearow C
Taillow C
Pidove C
Hoothoot C
Starly C
Lillipup U
Poochenya U
Shinx U
Ledyba C
Abra * (will teleport as soon as battle begins)
Ralts * (will flee as soon as battle begins)
Skitty U
Audino U
Eevee **

Route 2:
Levels are between 4 and 7
Shellos C
Hoppip C
Wooper C
Lotad C
Nincaida C
Barboach C
Surskit C
Marill U
Wingull C
Purrloin U
Blitzle U
Timburr C
Tympole C
Shelmet C
Buizel C

Gabron Ruins:
Levels are between 8 and 15
Nosepass *
Baltoy C
Ditto **
Natu C
Unown C
Lunatone U
Solrock U
Sigiplyph U
Yamask C
Dwebble C
Sandile C
Golett *
Spiritomb **

Route 3 (Ammoa - Icunga Forest):
Levels are between 8 and 13
Farfetch'd C
Audino U
Chansey *
Tangela *
Sunkern C
Yanma C
Pineco U
Snubbull C
Shuckle U
Whismur C
Chatot U
Meowth C
Mincinno U
Emolga *

Route 3 (Ammoa - Addobe):
Levels are between 12 and 17
Numel C
Trapinch C
Sandshrew C
Cacnea C
Sandile C
Maractus U
Darumaka C
Solosis U
Slugma C
Skorupi C
Hippopotas C
Aron U
Torkoal U
Dwebble C
Scraggy U
Sigilyph U

Route 4 (Addobe - Emmoco):
Levels are between 15 and 18
Cacnea C
Numel C
Sandshrew C
Sandile C
Solosis U
Sudowoodo *
Torkoal U
Pansear U
Timburr C
Klink C
Mienfoo C

Route 4 (Emmoco - Asude):
Levels are between 19 and 25
Surskit C
Gulpin C
Spinda U
Swablu C
Drifloon U
Buneary C
Glameow C
Stunky C
Croagunk U
Tympole C
Shelmet C
Foongus C
Litwick U
Stunfisk C

Emmoco Lake:
Levels are between 20 and 26
Corphish U
Poliwag C
Magikarp C
Feebas*
Shellder C
Krabby C
Horsea C
Goldeen C
Marill U
Quilfish U
Luvdisc C
Finneon C
Basculin C
Ducklett C

Asude Lake:
Levels are between 19 and 25
Psyduck C
Frillish C
Corphish U
Carvahna U
Zubat C
Quilfish U
Spheal U
Croagunk C
Basculin C

Icunga Forest:
Levels are between 23 and 27
Seedot C
Caterpie C
Wurmple C
Weedle C
Spinarak C
Shroomish U
Oddish C
Bellsprout C
Paras C
Venonat C
Pikachu U
Chansey *
Scyther *
Pinsir *
Yanma C
Pineco C
Teddiursa C
Kricketot C
Burmy C
Carnivine U
Sewaddle C
Venipede C
Joltik U
Karrablast C
Combee C
Aipom *

Route 5 (Flawna Village):
Levels are between 23 and 29
Ekans C
Roselia U
Clefairy U
Jigglypuff U
Mareep C
Teddiursa C
Stantler U
Smeargle *
Miltank U
Buneary C
Munna C
Purrloin C
Deerling C

Route 5 (Asude):
Levels are between 22 and 26
Ekans C
Nidoran C
Gastly U
Misdreavus U
Drowzee C
Koffing C
Spearow C
Taillow C
Murkrow C
Houndour C
Poochyena c
Spoink U
Duskull U
Rotom **
Zorua **
Foongus C
Rufflet C


Route 6 (Port Riplye):
Levels are between 24 and 30
Slowpoke C
Dratini **
Volbeat C
Illumise C
Gulpin C
Spinda U
Swablu C
Castform*
Tropius U
Cherubi C
Drifloon U
Panpour C
Cottonee C
Petilil C
Trubbish C
Gothita U
Grimer C

Route 6 (Mosnia Valley)
Levels are between 24 and 30
Tangela *
Exeggcute C
Shuckle U
Stantler U
Swablu C
Zangoose U
Seviper U
Tropius U
Chimecho C
Pachirisu C
Cherubi C
Carnivine C
Pansage C
Sewaddle C
Venipede C
Deerling C
Karrablast C
Joltik U
Ferroseed U
Druddigon *
Mankey C
Lickitung U
Kecleon *

Mt. Fros Cave:
Levels are between 33 and 37
Magnemite C
Mawile *
Sableye *
Diglett C
Seel C
Steelix *
Aron U
Voltorb C
Jynx U
Golbat C
Swoobat C
Wobbuffet *
Dunsparce U
Slugma C
Axew *
Cryogonal C
Swinub C
Delibird *

Mt. Fros:
Levels are between 33 and 37
Snover U
Snorunt U
Sneasel *
Geodude C
Graveler U
Roggenrola C
Boldore U
Onix C
Hitmonlee *
Hitmonchan *
Rhyhorn U
Larvitar **
Bagon**
Vanillite C
Cubchoo *
Swinub C

Route 6 (Zidoa Island):
Levels are between 22 and 29
Slowpoke C
Drowzee C
Heracross*
Exeggcute C
Psyduck C
Mr. Mime *
Togepi**
Natu C
Girafarig U
Meditite C
Spoink U
Bronzor U
Woobat U
Gothita U
Shelmet C
Elgyem U

Sea Route 1:
Levels are between 27 and 31
Corsola U
Mantine *
Horsea C
Krabby C
Remoraid C
Wailmer U
Sharpedo U
Tentacool C
Clamperl U
Chinchou U
Magikarp C
Staryu U
Lapras *
Dratini **
Relicanth *
Basculin C
Alomomola U

Lake Zidoa
Levels are between 24 and 27
Slowpoke C
Basculin C
Tentacool C
Psyduck C
Remoraid C
Shellder C
Ducklett C
Dratini **
Alomomola U
Tynamo *
Grimer C

Route 7 (Deres):
Levels are between 27 and 32
Diglett C
Spearow C
Sandshrew C
Magnemite C
Cubone C
Rhyhorn U
Porygon **
Heracross *
Phanpy C
Zangoose U
Solrock U
Burmy C
Roggenrola C
Throh U
Mienfoo C

Route 7 (Braitto):
Levels are between 30 and 33
Gligar C
Skarmory U
Makuhita C
Cubone C
Rhyhorn C
Phanpy C
Meditite C
Lunatone U
Absol U
Burmy C
Geodude C
Drilbur U
Sawk U
Mienfoo C
Scraggy C
Rufflet U

Route 8 (Genesia):
Levels are between 31 and 39
Slakoth U
Electrike C
Plusle C
Minun C
Kangaskhan *
Tauros U
Bouffalant U
Snorlax *
Mareep C
Hoppip C
Yanma C
Druddigon *
Beldum**
Bagon**
Ferroseed U
Rufflet U
Vullaby C

Route 8 (Asude):
Levels are between 33 and 41
Roselia C
Budew C
Growlithe C
Ponyta C
Doduo C
Cubone C
Koffing C
Tauros U
Bouffalant U
Murkrow C
Houndour C
Poochyena U
Seviper U
Shuppet C
Gothita U
Zorua **
Litwick *
Pawniard U
Vulpix U

Victory Road:
Levels are between 37 and 41
Machop C
Makuhita C
Electabuzz *
Magmar *
Marowak C
Onix C
Excadrill U
Durant C
Heatmor U
Deino **
Golbat C
Swoobat C
Larvitar **
Gible **
Riolu **
Sandile C
Scraggy C
Klink C
Druddigon *
Pawniard U
Larvesta **