The number you may see near their names is the level required, except the special condition.
I like to call them Stoners :
Pikachu → Raichu Thunderstone
Nidorina → Nidoqueen Moon Stone
Nidorino → Nidoking Moon Stone
Clefairy → Clefable Moon Stone
Vulpix → Ninetales Fire Stone
Jigglypuff → Wigglytuff Moon Stone
Gloom → Vileplume Leaf Stone
Gloom → Bellossom Sun Stone
Growlithe → Arcanine Fire Stone
Poliwhirl → Poliwrath Water Stone
Weepinbell → Victreebel Leaf Stone
Shellder → Cloyster Water Stone
Exeggcute → Exeggutor Leaf Stone
Staryu → Starmie Water Stone
Eevee → Vaporeon Water Stone
Eevee → Jolteon Thunderstone
Eevee → Flareon Fire Stone
Togetic → Togekiss Shiny Stone
Sunkern → Sunflora Sun Stone
Murkrow → Honchkrow Dusk Stone
Misdreavus → Mismagius Dusk Stone
Lombre → Ludicolo Water Stone
Nuzleaf → Shiftry Leaf Stone
Kirlia → Gallade Dawn Stone (Male)
Skitty → Delcatty Moon Stone
Roselia → Roserade Shiny Stone
Snorunt → Froslass Dawn Stone (Female)
Pansage → Simisage Leaf Stone
Pansear → Simisear Fire Stone
Panpour → Simipour Water Stone
Munna → Musharna Moon Stone
Cottonee → Whimsicott Sun Stone
Petilil → Lilligant Sun Stone
Minccino → Cinccino Shiny Stone
Eelektrik → Eelektross Thunderstone
Lampent → Chandelure Dusk Stone
Floette → Florges Shiny Stone
Doublade → Aegislash
Blade Forme Dusk Stone
Helioptile → Heliolisk Sun Stone
Trading:
Poliwhirl → Politoed King's Rock
Kadabra → Alakazam
Machoke → Machamp
Graveler → Golem
Slowpoke → Slowking King's Rock
Haunter → Gengar
Onix → Steelix Metal Coat
Rhydon → Rhyperior Protector
Seadra → Kingdra Dragon Scale
Scyther → Scizor Metal Coat
Electabuzz → Electivire Electrizer
Magmar → Magmortar Magmarizer
Porygon → Porygon2 Up-Grade
Porygon2 → Porygon-Z Dubious Disc
Dusclops → Dusknoir Reaper Cloth
Clamperl → Huntail Deepseatooth
Clamperl → Gorebyss Deepseascale
Boldore → Gigalith
Gurdurr → Conkeldurr
Karrablast → Escavalier Trade with Shelmet
Shelmet → Accelgor Trade with Karrablast
Spritzee → Aromatisse Trade holding Sachet
Swirlix → Slurpuff Trade holding Whipped Dream
Phantump → Trevenant
Pumpkaboo
Average Size → Gourgeist
Average Size
Happiness :
Pichu → Pikachu
Cleffa → Clefairy
Igglybuff → Jigglypuff
Golbat → Crobat
Chansey → Blissey
Eevee → Espeon Daytime
Eevee → Umbreon Nighttime
Munchlax → Snorlax
Togepi → Togetic
Azurill → Marill
Budew → Roselia Daytime
Chingling → Chimecho Nighttime
Buneary → Lopunny
Riolu → Lucario Daytime
Woobat → Swoobat
Swadloon → Leavanny
Others :
Magneton → Magnezone in a Magnetic Field area
Tyrogue → Hitmonlee 20 Attack > Defense
Tyrogue → Hitmonchan 20 Attack < Defense
Tyrogue → Hitmontop 20 Attack = Defense
Lickitung → Lickilicky after Rollout learned
Happiny → Chansey Daytime (holding Oval Stone)
Tangela → Tangrowth after AncientPower learned
Mime Jr. → Mr. Mime after Mimic learned
Eevee → Leafeon near a Mossy Rock
Eevee → Glaceon near an Icy Rock
Eevee → Sylveon maximum Affection in Pokémon Amie and knows a Fairy-type move
Bonsly → Sudowoodo after Mimic learned
Aipom → Ambipom after Double Hit learned
Yanma → Yanmega after AncientPower learned
Gligar → Gliscor Nighttime (holding Razor Fang)
Sneasel → Weavile Nighttime (holding Razor Claw)
Piloswine → Mamoswine after AncientPower learned
Mantyke → Mantine with Remoraid in party
Wurmple → Silcoon 7 Random, based on personality
Wurmple → Cascoon 7 Random, based on personality
Nincada → Shedinja 20 with empty spot in party
Nosepass → Probopass in a Magnetic Field area
Feebas → Milotic Beauty
Burmy → Mothim 20 Male
Burmy → Wormadam
Plant Cloak 20 Female, outside
Burmy → Wormadam
Sandy Cloak 20 Female, in caves
Burmy → Wormadam
Trash Cloak 20 Female, in buildings
Combee → Vespiquen 21 Female
Karrablast → Escavalier Trade with Shelmet
Shelmet → Accelgor Trade with Karrablast
Pancham → Pangoro 32 with a Dark type Pokémon in party
Inkay → Malamar 30 holding 3DS upside down
Tyrunt → Tyrantrum 39 Daytime
Amaura → Aurorus 39 Nighttime
Sliggoo → Goodra 50 during rain
Special Cases:
Feebas has 2 different ways of evolving. You can either trade it holding the Prism Scale, or you can max out its beauty by giving it Poke'Blocks that raises its beauty. Right after the beauty is maxed, just level it up.
Source
