No I am not talking about eevee
This is for the people who don't know about the effort values of pokemon

As everyone know training pokemon is the best way to go but theres a trick,
say for instance you fought a zubat and leveled up a pokemon will get 2 speed points for doing this now I am not saying battle zubats until you get the maximum 'cough255' but try to keep battling pokemon that give you the stat ups you need so any legendary pokemon will give you at least 2 of a stat therefore
giving you an advantage in 2 types but you can only maximize 2 stats you can then give them the perminant upgrade item of which you can buy in just about any game to maximize your favorite or the best stat for that pokemon these are what I was thinking of but others might disagree

grass-sp.attack,sp defense
fire-sp.attack,defense
water-sp.attack,sp. defense
normal-attack,defense
electric-sp.attack,speed
fighting-attack,defense
psychic-sp.attack,sp.defense
ghost-sp.attack,sp.defense
poison-attack/sp.attack,defense
steel-attack,defense
dark-sp.attack,defense
flying-attack,speed
ground-attack/sp.attack,sp.defense
rock-attack/sp.attack,sp.defense
dragon-sp.attack,attack
? ? ?(arceus)-not sure

I f havn't explained this thoroughly enough then tell me