yeah balanced EV spreads like that haven't been seen since Gen 1-2, and only because those games didn't have a total EV limit and the way EVs were gained were based on the base stats of the pokemon being fought, rather than static values assigned to each Pokemon. It was a completely different system and part of the reason why Gen 2 -> Gen 3 compatibility doesn't exist.
Chesnaught prefers 252 HP/ 252 Def anyway :p
Its simple. For Gen 3-6, whenever you catch a Pokemon, the game randomly generates a value between 0 and 31 for each of the six stats. In Gen 6, certain Pokemon such as stationary Legendaries, wild baby Pokemon, and Pokemon caught in Friend Safari are guaranteed to have at least 3 (Legendaries & Babies) or 2 (Friend Safar) of their stats set to 31. These values are set in stone as soon as you encounter/receive the Pokemon, and cannot be changed without hacking. These values, in conjunction with the Pokemon's base stats and EVs, are used to determine the Pokemon's actual stats using the following formulas:
HP stat = (IV+(basestat*2)+int(EVs/4)+100)*(level/100)+10
All other stats = ((IV+(basestat*2)+int(EVs/4))*(level/100)+5)*nature
Assuming neutral natures, at level 100 these formulas simplify to the following:
HP stat = IV+(basestat*2)+int(EVs/4)+110
All other stats = (IV+(basestat*2)+int(EVs/4)+5)*nature
At level 100, this has the effect of essentially adding 1 stat point for each IV in that stat. A level 100 Pokemon with an IV of 0 in any given stat will essentially have 31 points less in that stat than if the Pokemon had the maximum value of 31.
In Gen 1-2, the formula is more or less the same, except for the following differences:
IVs only range from 0-15, rather than 0-31, so the IV is multiplied by 2 in the above formulas.
Natures didn't exist, so there is no modifier
Sp.Atk and Sp.Def use the exact same IV, as opposed to having separate IVs like in Gen 3 onward. This was done to retain compatibility with Gen 1.
While the HP stat has its own IV, it is directly determined by the other four IVs in the following manner:
If the IV value for Special is odd, add 1, otherwise add 0.
If the IV value for Speed is odd, add 2, otherwise add 0.
If the IV value for Defense is odd, add 4, otherwise add 0.
If the IV value for Attack is odd, add 8, otherwise add 0.
Because of the way the EV system works in Gen 1-2, the value for EVs that is calculated in the stat formula instead uses sqrt(EV)/4. The reason for this is due to the fact that EVs in Gen 1-2 ranged from 0-65535, as opposed to 0-255 in later generations.