EV-training locations

Effort Values, colloquially abbreviated as EVs, are statistical determinants that are calculated into the eventual upgrowth of your Pokémon's stats. They are the teal-colored stats shown in your Pokémon's stats on their hover-over card in-game.

EVs are really important if you want to be succesfull in PvP (Player vs Player) battles but it can also be helpful if you are only interested in story.

EVspots

Kanto

EV	Map	Area	Daytime	Pokemon
ATK	Route 24	Surf	Day	Krabby, Kingler, Seaking
DEF		Surf, Fishing	Morning	Koffing, Weezing, Poliwrath
SPD		Land	Day	Pidgey, Pidgeotto, Pidgeot
SPATK		Land	Night	Oddish, Gloom, Vileplume
SPDEF		Surf, Fishing	Night	Tentacool, Tentacruel, Slowking
HP		Land	Morning	Caterpie, Jigglypuff, Wigglytuff

Johto

EV	Map	Area	Daytime	Pokemon
ATK	Route 31	Land	Morning	Sentret, Nuzleaf, Shiftry
DEF		Land	Day	Sandshrew, Sandslash, Golem
SPD		Surf, Fishing	Morning	Zubat, Golbat, Crobat
SPATK		Land	Night	Gastly, Haunter, Gengar
SPDEF		Surf, Fishing	Night	Seel, Lombre, Ludicolo
HP		Surf	Day	Wooper, Quagsire, Azumarill

Hoenn

EV	Map	Area	Daytime	Pokemon
ATK	Route 120	Land	Day	NidoranM, Nidorino, Nidoking
DEF		Surf, Fishing	Night	Koffing, Pelipper, Poliwrath
SPD		Surf, Fishing	Day	Zubat, Golbat, Crobat
SPATK		Land	Morning	Mareep, Flaffy, Ampharos
SPDEF		Surf, Fishing	Morning	Seel, Mantine, Politoed
HP		Land	Night	NidoranF, Nidorina, Nidoqueen

Shinnoh

EV	Map	Area	Daytime	Pokemon
ATK	Route 208	Land	Night	Patrat, Kricketune, Staraptor
DEF		Surf, Fishing	Morning	Koffing, Weezing, Poliwrath
SPD		Surf, Fishing	Night	Zubat, Golbat, Crobat
SPATK		Land	Day	Gastly, Haunter, Gengar
SPDEF		Surf, Fishing	Day	Seel, Lombre, Ludicolo
HP		Land	Morning	Dunsparce, Lickitung, Lickilicky

All regions

Other mentionable spots

EV	Map	Area	Daytime	Pokemon	Avoid this Pokemon	Lvl
SPDEF	Route 41	Surf	Morning, Day	Tentacool, Tentacruel, Mantine	Lanturn (2 HP)	30-35

Notes

Route 41 is also good to level up your pokemons because that is a lvl 30-35 map.