Hello there!
Having found BIGJRA’s resource immensely useful during my Pokemon Reborn monotype runs, I was looking for something similar for this game. The man himself made a version some 5-6 years ago, which is now obviously outdated, and I couldn’t find anything more recent. So I took it upon myself to compile a guide myself. After unguided monoice and monofighting playthroughs (and lots of time looking through the route encounters on the wiki) I think I’ve achieved something fairly accurate. It goes up to the Pokémon League as of now, so Pokemon relegated to the post-game, like some Deltas and most Legendaries, aren’t included. If you notice any errors, please do not hesitate to make a comment and I will correct it!
Thanks to BIGJRA for inspiration and for formatting, which I am shamelessly copying 
Updated to version 1.2.7
This is a list that shows what different Pokemon are available at any given time in game in a monotype run.
Each spoiler represents one section of the game, separated by certain level-capped fights on Hard difficulty. They include the most readily available member of the evolution line of the Pokemon, and do not mention Pokemon available in previous areas—though many evolved Pokemon can be found in the wild at later stages, allowing simpler acquisition, this guide’s sole focus is on when a Pokemon is first available. In cases where two evolutions of the same family become available simultaneously, the earliest evolution will be listed. Pokemon that first become available in the Friend Safari will be listed once more when they are able to be encountered elsewhere. The guide may not be completely accurate if playing with Purity Mode enabled.
Eevee is listed once more when it becomes available to players who did not choose it as a starter.
- Italics indicate Pokemon that will evolve into a given type.
- Underline indicates Pokemon that will lose that type by their final evolution (mainly for collecting).
-
Strikethroughindicates Pokemon which will have a mega-evolution that changes into the target type, such as Sceptile → Dragon. Whether or not these are legal for your monotype run prior to obtaining the appropriate mega stone, or at all, is up to you. - An asterisk* indicates Pokemon available earlier than the given section via Friend Safari.
All types that do not feature any new Pokemon will be listed at the bottom of each spoiler.
Starters
Dark: D. Squirtle, Eevee
Dragon: D. Charmander
Electric: Eevee
Fairy: D. Bulbasaur, Eevee
Fighting: D. Squirtle
Fire: Eevee
Ghost: D. Charmander
Grass: Eevee
Ice: Eevee
Normal: Eevee
Psychic: D. Bulbasaur, Eevee
Water: Eevee
Nothing new: Bug, Flying, Ground, Poison, Steel, Rock
Beginning to Trainer School
Bug: Caterpie, Durant, Dwebble, Shuckle, Weedle
Dark: Poochyena, Purrloin, Stunky
Electric: Blitzle, Elekid, Pikachu, Rotom
Fairy: Blitzle, Carbink
Fire: Heatmor, Onix, Ponyta
Flying: Hoppip, Woobat, Zubat
Ghost: Gastly, Rotom
Grass: Exeggcute, Hoppip
Ground: Baltoy, Bunnelby, Diglett, Drilbur, Geodude, NidoranF, NidoranM, Onix, Phanpy
Normal: Bunnelby, Patrat, Meowth
Poison: Gastly, NidoranF, NidoranM, Stunky, Zubat
Psychic: Abra, Baltoy, Exeggcute, Woobat
Rock: Carbink, Geodude, Dwebble, Nosepass, Onix, Roggenrola, Shuckle
Steel: Drilbur, Durant, Nosepass, Onix
Nothing new: Dragon, Fighting, Ice, Water
Trainer School to Suntouched Gym
Dark: Magikarp, Pancham, Sableye
Dragon: Axew
Electric: Magnemite
Fairy: D. Dwebble, Marill
Fighting: Machop, Magikarp, Makuhita, Pancham, Riolu, Timburr, Tyrogue
Flying: Natu
Ghost: Sableye
Ground: D. Grimer, Sandshrew
Ice: Shellder
Normal: Whismur
Poison: Qwilfish
Psychic: Natu
Rock: Corsola, Relicanth
Steel: Axew, Magnemite, Riolu
Water: Barboach, Bidoof, Buizel, Carvanha, Clamperl, Corphish, Corsola, Finneon, Goldeen, Magikarp, Marill, Qwilfish, Relicanth, Remoraid, Shellder, Staryu, Totodile
Nothing new: Bug, Fire, Grass
Suntouched Gym to Nora (Metchi Town)
Dark: Seedot
Dragon: Charmander
Fairy: Ralts
Fighting: D. Scyther, Poliwag, Sawk, Throh
Fire: Charmander
Flying: Charmander, Mantyke
Ghost: D. Aipom
Grass: Lotad, Pansage, Petilil, Seedot, Sudowoodo
Ground: Wooper, Shellos
Ice: D. Scyther, Seel
Normal: D. Aipom
Poison: Tentacool
Psychic: Ralts
Rock: Sudowoodo
Steel: Piplup
Water: Alomomola, Basculin, Clauncher, Krabby, Lotad, Mantyke, Oshawott, Panpour, Piplup, Poliwag, Seel, Shellos, Tentacool, Wooper
Nothing new: Bug, Electric
Friend Safari slot 1
Bug: Combee, Burmy, Karrablast, Illumise, Ledyba, Paras, Scatterbug, Sewaddle, Shedinja, Spinarak, Surskit, Venonat, Volbeat, Wurmple
Dark: Houndour, Inkay
Dragon: Seadra, Swablu
Electric: Dedenne, Emolga, Helioptile, Minun, Pachirisu, Plusle, Stunfisk,
Fairy: Clefairy, Dedenne, Jigglypuff, Mr. Mime, Snubbull, Spritzee, Swablu
Fighting: Mankey
Fire: Houndour, Litleo, Magmar, Numel, Pansear, Slugma, Torkoal,
Flying: Chatot, Combee, Ducklett, Drifloon, Emolga, Farfetch’d, Ledyba, Pidgey, Pidove, Starly, Swablu, Taillow, Wurmple
Ghost: Drifloon, Misdreavus, Pumpkaboo, Shedinja, Shuppet
Grass: Carnivine, Cherubi, Foongus, Maractus, Oddish, Paras, Pumpkaboo, Sewaddle, Snover, Sunkern, Weepinbell
Ground: Numel, Stunfisk
Ice: Amaura, Cubchoo, Lapras, Snover, Vanillish
Normal: Chatot, Dunsparce, Glameow, Herdier, Lickitung, Litleo, Rattata, Sentret, Skitty, Stantler, Starly, Swablu,Teddiursa, Zigzagoon
Poison: Ekans, Foongus, Gulpin, Oddish, Spinarak, Trubbish, Weepinbell, Wurmple
Psychic: Bronzor, Drowzee, Elgyem, Espurr, Lunatone, Mr. Mime, Solrock, Spoink, Unown
Rock: Slugma, Lunatone, Solrock
Steel: Bronzor, Karrablast, Klang
Water: Chinchou, Lapras, Luvdisc, Psyduck, Seadra, Slowpoke, Wailmer
Nora (Metchi Town) to Vipik Gym
Bug: Anorith
Dragon: Skrelp, Tyrunt
Electric: D. Ralts
Fairy: Togepi
Fire: Cyndaquil, D. Sunkern, D. Wooper
Flying: Aerodactyl, Archen, Doduo, Ducklett, Fearow, Togepi, Wingull
Ghost: Frillish
Grass: D. Wooper, Lileep
Ground: Mudkip, Tympole
Ice: Amaura, D. Ralt
Normal: Doduo, Fearow, Furfrou, Minccino
Poison: D. Sunkern, Skrelp
Rock: Aerodactyl, Amaura, Anorith, Archen, Cranidos, Kabuto, Lileep, Omanyte, Shieldon, Tirtouga, Tyrunt
Steel: Shieldon
Water: Frillish, Ducklett, Kabuto, Mudkip, Omanyte, Skrelp, Squirtle, Tirtouga, Tympole, Wingull
Nothing new: Dark, Fighting, Psychic
Vipik Gym to Damian (Rezzai Cavern)
Bug: Vibrava
Dark: D. Pidgey, Krokorok
Dragon: D. Pidgey, Seadra, Swablu*, Vibrava
Electric: Electrike, Lanturn, Luxray
Fairy: Cottonee, Floette, Mime Jr.*, Swablu
Fire: Growlithe, Fennekin, Fletchling
Flying: Fletchling, Swablu
Ghost: Marowak
Grass: Cottonee, Roselia, Servine, Weepinbell*
Ground: Hippopotas, Krokorok, Marowak, Vibrava
Ice: Sneasel
Normal: Castform, Ditto, Dunsparce, Girafarig, Kecleon, Flecthling, Swablu
Poison: Grimer, Gulpin*, Roselia, Venipede, Weepinbell*
Psychic: Girafarig, Slowpoke*
Water: Lanturn, Psyduck*, Seadra*, Slowpoke*
Nothing new: Fighting, Rock, Steel
Damian (Rezzai Cavern) to Helios Gym
Bug: Heracross, Larvesta, Pinsir, Scyther
Dark: Eevee
Dragon: Bagon, Goomy, Mareep
Electric: Emolga*, Mareep, Minun*, Pachirisu*, Plusle*
Fairy: Chikorita, Clefairy*, Eevee, Milotic
Fighting: Heracross
Fire: Eevee, Larvesta
Flying: Bagon, Chatot*, Pinsir, Starly*
Ghost: Phantump*, Pumpkaboo*, Yamask
Grass: Chikorita, Eevee, Gogoat, Phantump*, Pumpkaboo*
Ice: Eevee, Lapras*, Smoochum
Normal: Chatot*, Eevee, Gogoat, Porygon, Skitty, Smeargle, Starly*, Stoutland*
Poison: Koffing
Psychic: Chimecho, D. Lotad, Eevee, Smoochum, Solosis, Wynaut
Water: D. Lotad, Eevee, Lapras*, Milotic
Nothing new: Ground, Rock, Steel
Helios Gym to Sonata Gym
Dark: D. Budew
Dragon: Dragonair, Druddigon, Treecko
Electric: D. Koffing
Fairy: D. Budew, D. Litwick, Klefki, Slurpuff, Spritzee*
Fighting: Hawlucha, Primeape*
Fire: D. Combee, D. Litwick, Litwick, Ninetales, Slugma, Sunkern, Torkoal
Flying: D. Koffing, Tropius
Ghost: Banette*, Dusclops, Glalie (breed + evolve), Honedge, Litwick, Mismagius
Grass: D. Munchlax, Sunkern, Treecko, Tropius
Ground: Rhyhorn
Ice: Cryogonal, Glalie, Spheal
Normal: Chansey, Kangaskhan, Raticate*, Snorlax
Rock: Lairon, Rhyhorn, Slugma
Steel: D. Combee, Honedge, Klefki, Lairon
Water: Spheal, Wailmer*
Nothing new: Bug, Poison, Psychic
Sonata Gym to Kepler Gym
Bug: D. Dunsparce
Dark: D. Clamperl
Dragon: D. Clamperl
Fairy: D. Clamperl
Fighting: Chespin
Grass: Chespin, Maractus*, Turtwig
Ground: Turtwig
Psychic: Beldum
Steel: Beldum
Water: D. Dunsparce
Nothing new: Electric, Fire, Flying, Ghost, Ice, Normal, Poison, Rock
Kepler Gym to Selene Gym
Bug: Ariados*, Vivillon, Yanmega
Dark: Absol, Deino, Honchkrow, Pupitar, Scraggy
Dragon: Deino, Noivern
Electric: Eelektross, Joltik
Fairy: Audino, D. Liepard, Mawile
Fighting: Chimchar, Mienfoo, Scraggy
Fire: Camerupt*, Chimchar, Darmanitan, Magmar*, Simisear*
Flying: Delibird, Honchkrow, Noivern, Sigilyph, Vivillon, Yanmega
Ghost: D. Liepard, Golurk
Grass: Bulbasaur, Cacturne, D. Noibat, D. Scraggy, Tangrowth,
Ground: Camerupt*, Golurk, Pupitar
Ice: Delibird
Normal: Audino, Miltank, Spinda, Vigoroth
Poison: D. Shinx, Drapion
Psychic: Sigilyph
Rock: Pupitar
Steel: D. Noibat, D. Shinx, Klink*, Mawile
Water: Froakie
Friend Safari slot 2
Bug: Pineco, Shelmet
Dark: Gothorita, Spiritomb, Zorua
Electric: Voltorb
Fighting: Buneary, Combusken, Pignite
Fire: Combusken, Pignite
Flying: Hoothoot, Skarmory
Ghost: Spiritomb
Normal: Aipom, Bouffalant, Buneary, Hoothoot
Poison: Seviper
Psychic: Gothorita, Munna
Rock: Binacle
Steel: Ferroseed, Skarmory, Pawniard
Water: Binacle
Nothing new: Dragon, Fairy, Grass, Ground, Ice
Selene Gym to Amphitrite Gym
Bug: Accelgor*, Dustox*, Escavalier*, Ninjask, Parasect*, Shedinja
Dragon: D. Bergmite, Gible
Electric: D. Cyndaquil, Thundurus
Fairy: Granbull*
Fighting: D. Shuckle
Fire: D. Snorunt
Flying: Dustox* (breed + evolve), Ninjask, Thundurus
Ghost: D. Snorunt, D. Solosis, Shedinja
Grass: Bellossom, Parasect*, Sawsbuck
Ground: Gible
Normal: Linoone, Sawsbuck, Stantler*, Zangoose
Poison: Dustox*
Psychic: D. Geodude, Grumpig* , Hypno*
Rock: Barbaracle*, D. Bergmite, D. Geodude, D. Snorunt, D. Solosis
Steel: D. Cyndaquil, D. Shuckle, Escavalier*
Water: Barbaracle*
Nothing new: Dark, Ice
Amphitrite Gym to Erebus Gym
Bug: D. Metang, Ledian*
Dark: Malamar*
Dragon: D. Growlithe
Electric: Heliolisk*
Fairy: D. Misdreavus
Fighting: Emboar*, Torchic**
Fire: D. Chinchou, Emboar, Torchic*
Ghost: D. Chinchou
Grass: Abomasnow*
Ground: D. Metang, Mamoswine
Ice: Abomasnow*, Avalugg, Beartic*, D. Misdreavus, Mamoswine, Vanilluxe*
Normal: D. Growlithe, Furret, Heliolisk*, Lickitung
Poison: D. Girafarig, D. Heatmor, D. Yamask
Psychic: Bronzong*, D. Doduo, Malamar*, Musharna*
Steel: Bronzong*, D. Girafarig, D. Heatmor, D. Yamask
Nothing new: Flying, Rock, Water
Friend Safari slot 3
Dark: Vullaby
Fighting: Croagunk, Meditite
Flying: Gligar, Rufflet, Vullaby
Ground: Gligar
Normal: Rufflet, Tauros
Poison: Croagunk
Psychic: Meditite
Nothing new: Bug, Dragon, Electric, Fairy, Fire, Ghost, Grass, Ice, Rock Steel, Water
Erebus Gym to Pokemon League
Fire: D. Petilil (Water)
Water: D. Petilil (Water)
Nothing new: Bug, Dark, Dragon, Electric, Fairy, Fighting, Flying, Ghost, Grass, Ground, Ice, Normal, Poison, Psychic, Rock, Steel
Post-game
Everything else (WIP!)
i forget