IVs (Individual Values) are part of what make individual Pokemon different. Say you catch two Sentret. One has higher stats than the other, even though both are untrained and at the same level. It's most likely because it has better IVs.
IVs can range from 0-31, with 31 being the highest, and are determined when you encounter a wild Pokemon or when you pick up an egg from the Daycare. After they're determined, they can't be changed except through the use of a cheating device.
EVs (Effort Values) help determine the sort of stat growth a Pokemon gets by leveling. Every time you defeat a Pokemon (as long as you gain exp.) your Pokemon gets a certain amount of EVs. 4 EVs in one stat = +1 to that stat at level 100.
The amount of EVs you can get for a Pokemon is capped at 510, and the maximum number you can have in any one stat is 255 (though you can cap it at 252 and get the same result). Maxing out the EVs on a stat means you end up with a +63 to that stat at level 100. EVs can be removed through the use of certain Berries, while Pokerus doubles the amount of EVs you receive when you defeat a Pokemon.
Hopefully that made sense, I'm not 100% awake yet. ^^;
That made the basic amount of sense, thanks. :D But how do you no where it is at along the 252 on EV's? I have a team that does pretty good but it doesn't really have a focus nor did I train using the info of EV's, I just trained them because I like the pokemon.
How would I want to go about making these pokemon I like, into a viable team:
Dragonite, Kingdra, Umbreon, Kabutops, Espeon, Gardevoir, Arcanine, Zangoose, Victreebel
My current team setup is like this:
Heracross: 324 HP
Attack 280
defense 201
sp attack 118
sp defense 246
speed 205
megahorn, close combat, brick break, aerial ace
kingdra: 290 HP
Attack 222
defense 220
sp attack 216
sp defense 272
speed 203
surf, brine, dragon pulse, ice beam
Houndoom: 295 HP
Attack 215
defense 151
sp attack 246
sp defense 209
speed 245
crunch, faint attack, flamethrower, shadow ball
Venusaur: 310HP
Attack 199
defense 221
sp attack 236
sp defense 237
speed 183
solar beam, sludge bomb, earthquake, sunny day
Raichu: 257HP
Attack 221
defense 153
sp attack 226
sp defense 221
speed 250
thunderbolt, iron tail, dig, quick attack
Dragonite: 331HP
Attack 312
defense 250
sp attack 209
sp defense 232
speed 237
Outrage, Fly, Waterfall, Fire Punch
I never set up a strategy and just chose pokemon that covered a wide element type, using them all as hitters. Sorry if this is not enough info and such, just trying to get a good grasp of an actual competitive team.