(Updated by Pokemaster for Gen 9)
Quick stat: the most common species categories are Paradox (16 Pokemon), Dragon (8), Mouse (8), Fox (7) Mushroom (6), and Poison Pin (6).
Pokemon from different evolution lines:
Seed Pokemon:
Bulbasaur/Ivysaur/Venusaur
Sunkern
Flame Pokemon:
Charmeleon/Charizard
Flareon
Moltres
Infernape
Shellfish Pokemon:
Blastoise
Kabuto/Kabutops
Worm Pokemon:
Caterpie
Wurmple
Snom
Cocoon Pokemon:
Metapod/Kakuna
Silcoon/Cascoon
Butterfly Pokemon:
Butterfree
Beautifly
Tiny Bird Pokemon:
Pidgey
Spearow
Natu
Rookidee
Mouse Pokemon:
Rattata/Raticate
Pikachu/Raichu
Sandshrew/Sandslash
Pawmi/Pawmo
Poison Pin Pokemon:
Nidoran♀/Nidorina
Nidoran♂/Nidorino
Poipole/Naganadel
Drill Pokemon:
Nidoqueen
Nidoking
Rhydon/Rhyperior
Fairy Pokemon:
Clefairy/Clefable
Snubbull/Granbull
Fox Pokemon:
Vulpix/Ninetales
Fennekin/Braixen/Delphox
Nickit/Thievul
Balloon Pokemon:
Igglybuff/Jigglypuff/Wigglytuff
Qwilfish
Drifloon
Bat Pokemon:
Zubat/Golbat/Crobat
Woobat
Flower Pokemon:
Vileplume/Bellossom
Bellsprout
Mushroom Pokemon:
Paras/Parasect
Shroomish/Breloom
Foongus/Amoonguss
Poison Moth Pokemon:
Venomoth
Dustox
Mole Pokemon:
Diglett/Dugtrio
Drilbur
Puppy Pokemon:
Growlithe
Lillipup
Rockruff
Yamper/Fidough
Scout Pokemon:
Hisuian Growlithe
Sentret
Patrat
Tadpole Pokemon:
Poliwag/Poliwhirl/Poliwrath
Tympole
Sea Lion Pokemon:
Seel/Dewgong
Popplio
Bivalve Pokemon:
Shellder/Cloyster
Clamperl
Pincer Pokemon:
Kingler
Scizor
Egg Pokemon:
Exeggcute
Chansey
Dragon Pokemon:
Horsea/Seadra/Kingdra
Dratini/Dragonair/Dragonite
Salamence
Goodra
Star Shape Pokemon:
Staryu
Cleffa
Dancing
Galarian Mr. Mime
Oricorio
Electric Pokemon:
Elekid/Electabuzz
Zapdos
Stag Beetle Pokemon:
Pinsir
Vikavolt
Fish Pokemon:
Magikarp
Feebas
Lightning Pokemon:
Jolteon
Electrike
Fossil Pokemon:
Aerodactyl
Dracozolt
Arctozolt
Dracovish
Arctovish
Cruel:
Galarian Articuno
Liepard
Volcano Pokemon:
Quilava/Typhlosion
Entei
Light Pokemon:
Lanturn
Ampharos
Happiness Pokemon:
Togetic
Blissey
Mystic Pokemon:
Xatu
Flygon
Sun Pokemon:
Sunflora
Espeon
Volcarona
Darkness Pokemon:
Murkrow
Sableye
Royal Pokemon:
Slowking
Pyroar
Bagworm Pokemon:
Pineco/Forretress
Burmy/Wormadam
Armor Pokemon:
Donphan
Tyranitar
Bite Pokemon:
Poochyena/Mightyena
Drednaw
Wily Pokemon:
Nuzleaf
Impidimp
Water Bird Pokemon:
Pelipper
Ducklett
Emotion Pokemon:
Kirlia
Mesprit
Indeedee
Ninja Pokemon:
Ninjask
Greninja
Cheering Pokemon:
Plusle
Minun
Firefly Pokemon:
Volbeat
Illumise
Brutal Pokemon:
Sharpedo
Hydreigon
Coal Pokemon:
Torkoal
Rolycoly/Carkol/Coalossal
Manipulate Pokemon:
Grumpig
Gothorita
Vibration Pokemon:
Vibrava
Palpitoad/Seismitoad
Cactus Pokemon:
Cacnea
Maractus
Meteorite Pokemon:
Lunatone
Solrock
Fruit Pokemon:
Tropius
Bounsweet/Steenee/Tsareena
Iceberg Pokemon:
Regice
Avalugg
Eon Pokemon:
Latias
Latios
Continent Pokemon:
Groudon
Torterra
Chimp Pokemon:
Chimchar
Grookey
Playful Pokemon:
Monferno
Pancham
Penguin Pokemon:
Piplup/Prinplup
Eiscue
Rabbit Pokemon:
Buneary/Lopunny
Scorbunny/Raboot
Cave Pokemon:
Gabite
Druddigon
Thunderbolt Pokemon:
Electivire
Zebstrika
Fresh Snow Pokemon:
Glaceon
Vanillite
Devious Pokemon:
Purrloin
Morgrem
Ember Pokemon:
Simisear
Fletchinder
Drowsing Pokemon:
Musharna
Komala
Ore Pokemon:
Boldore
Glimmet/Glimmora
Flowering Pokemon:
Lilligant
Gossifleur
Hostile Pokemon:
Basculin
Zweilous
Snail Pokemon:
Shelmet
Hisuian Sliggoo
Trap Pokemon:
Stunfisk
Spidops
Mount Pokemon:
Skiddo/Gogoat
Cyclizar
Jewel Pokemon:
Carbink
Diancie
Larva Pokemon:
Grubbin
Blipbug
Land Spirit Pokemon:
Tapu Koko
Tapu Lele
Tapu Bulu
Tapu Fini
Paradox:
Great Tusk
Scream Tail
Brute Bonnet
Flutter Mane
Slither Wing
Sandy Shocks
Iron Treads
Iron Bundle
Iron Hands
Iron Jugulis
Iron Moth
Iron Thorns
Roaring Moon
Iron Valiant
Koraidon
Miraidon
Ruinous:
Wo-Chien
Chien-Pao
Ting-Lu
Chi-Yu
Pokemon from the same evolution line:
Bird Pokemon: Pidgeotto/Pidgeot
Weed Pokemon: Oddish/Gloom
Duck Pokemon: Psyduck/Golduck
Pig Monkey Pokemon: Mankey/Primeape
Psi Pokemon: Abra/Kadabra/Alakazam
Superpower Pokemon: Machop/Machoke/Machamp
Flycatcher Pokemon: Weepinbell/Victreebel
Jellyfish Pokemon: Tentacool/Tentacruel
Rock Pokemon: Geodude/Graveler
Fire Horse Pokemon: Ponyta/Rapidash
Unique Horn: Galarian Ponyta/Rapidash
Magnet Pokemon: Magnemite/Magneton
Wild Duck: Farfetch'd/Sirfetch'd
Sludge Pokemon: Grimer/Muk
Gas Pokemon: Gastly/Haunter
Hypnosis Pokemon: Drowzee/Hypno
Ball Pokemon: Voltorb/Electrode
Sphere Pokemon: Hisuian Voltorb/Electrode
Licking Pokemon: Lickitung/Lickilicky
Poison Gas Pokemon: Koffing/Weezing
Vine Pokemon: Tangela/Tangrowth
Goldfish Pokemon: Goldeen/Seaking
Virtual Pokemon: Porygon/Porygon2/Porygon-Z
Spiral Pokemon: Omanyte/Omastar
Leaf Pokemon: Chikorita/Bayleef
Big Jaw Pokemon: Totodile/Croconaw/Feraligatr
Owl Pokemon: Hoothoot/Noctowl
Five Star Pokemon: Ledyba/Ledian
Wool Pokemon: Mareep/Flaaffy
Cottonweed Pokemon: Hoppip/Skiploom/Jumpluff
Long Tail Pokemon: Aipom/Ambipom
Water Fish Pokemon: Wooper/Quagsire
Long Neck Pokemon: Girafarig/Farigiraf
Land Snake Pokemon: Dunsparce/Dudunsparce
Sharp Claw Pokemon: Sneasel/Weavile
Lava Pokemon: Slugma/Magcargo
Coral Pokemon: Galarian Corsola/Cursola
Jet Pokemon: Remoraid/Octillery
Kite Pokemon: Mantine/Mantyke
Dark Pokemon: Houndour/Houndoom
Big Horn Pokemon: Stantler/Wyrdeer
Wood Gecko Pokemon: Treecko/Grovyle
Mud Fish Pokemon: Mudkip/Marshtomp/Swampert
Compass Pokemon: Nosepass/Probopass
Iron Armor Pokemon: Aron/Lairon/Aggron
Meditate Pokemon: Meditite/Medicham
Whiskers Pokemon: Barboach/Whiscash
Clay Doll Pokemon: Baltoy/Claydol
Starling Pokemon: Starly/Staravia
Cricket Pokemon: Kricketot/Kricketune
Head Butt Pokemon: Cranidos/Rampardos
Shield Pokemon: Shieldon/Bastiodon
Sea Weasel Pokemon: Buizel/Floatzel
Sea Slug Pokemon: Shellos/Gastrodon
Skunk Pokemon: Stunky/Skuntank
Toxic Mouth Pokemon: Croagunk/Toxicroak
Frost Tree Pokemon: Snover/Abomasnow
Grass Snake Pokemon: Snivy/Servine
Fire Pig Pokemon: Tepig/Pignite
Muscular Pokemon: Timburr/Gurdurr/Conkeldurr
Desert Croc Pokemon: Sandile/Krokorok
Zen Charm Pokemon: Darumaka/Zen Mode Darmanitan
Prototurtle Pokemon: Tirtouga/Carracosta
First Bird Pokemon: Archen/Archeops
Season Pokemon: Deerling /Sawsbuck
Floating Pokemon: Frillish/Jellicent
Gear Pokemon: Klink/Klang/Klinklang
EleFish Pokemon: Tynamo/Eelektrik/Eelektross
Cerebral Pokemon: Elgyem/Beheeyem
Axe Jaw Pokemon: Fraxure/Haxorus
Martial Arts Pokemon: Mienfoo/Mienshao
Automaton Pokemon: Golett/Golurk
Spiny Armor Pokemon: Quilladin/Chesnaught
Bubble Frog Pokemon: Froakie/Frogadier
Digging Pokemon: Bunnelby/Diggersby
Scatterdust Pokemon: Scatterbug/Spewpa
Single Bloom Pokemon: Flabébé/Floette
Sword Pokemon: Honedge/Doublade
Mock Kelp Pokemon: Skrelp/Dragalge
Generator Pokemon: Helioptile/Heliolisk
Tundra Pokemon: Amaura/Aurorus
Soft Tissue Pokemon: Goomy/Sliggoo
Pumpkin Pokemon: Pumpkaboo/Gourgeist
Sound Wave Pokemon: Noibat/Noivern
Fire Cat Pokemon: Litten/Torracat
Bee Fly Pokemon: Cutiefly/Ribombee
Brutal Star Pokemon: Mareanie/Toxapex
Water Bubble Pokemon: Dewpider/Araquanid
Illuminating Pokemon: Morelull/Shiinotic
Toxic Lizard Pokemon: Salandit/Salazzle
Synthetic Pokemon: Type: Null/Silvally
Scaly Pokemon: Jangmo-o/Hakamo-o/Kommo-o
Hex Nut Pokemon: Meltan/Melmetal
Water Lizard Pokemon: Sobble/Drizzile
Raven Pokemon: Corvisquire/Corviknight
Sheep Pokemon: Wooloo/Dubwool
Dog Pokemon: Boltund/Dachsbun
Sand Snake Pokemon: Silicobra/Sandaconda
Radiator Pokemon: Sizzlipede/Centiskorch
Tantrum Pokemon: Clobbopus/Grapploct
Black Tea Pokemon: Sinistea/Polteageist
Cream Pokemon: Milcery/Alcremie
Copperderm Pokemon: Cufant/Copperajah
Warrior Pokemon: Zacian/Zamazenta
Wushu Pokemon: Kubfu/Urshifu
Grass Cat Pokemon: Sprigatito/Floragato
Fire Croc Pokemon: Fuecoco/Crocalor
Hog Pokemon: Lechonk/Oinkologne
Grasshopper Pokemon: Nymble/Lokix
Olive Pokemon: Smoliv/Dolliv/Arboliva
Rock Salt Pokemon: Nacli/Naclstack/Garganacl
Tumbleweed Pokemon: Bramblin/Brambleghast
Woodear Pokemon: Toedscool/Toedscruel
Spicy Pepper Pokemon: Capsakid/Scovillain
Rolling Pokemon: Rellor/Rabsca
Hammer Pokemon: Tinkatuff/Tinkaton
Garden Eel Pokemon: Wiglett/Wugtrio
Dolphin Pokemon: Finizen/Palafin
Ghost Dog Pokemon: Greavard/Houndstone
Terra Whale Pokemon: Cetoddle/Cetitan
Ice Fin Pokemon: Frigibax/Arctibax
Now I'm done
(If there is anything I missed, please tell me.)
