>>44207378A general thing, if you're investing in bulk, EVs should into low defensive stats, assuming you aren't trying to avoid getting hit by them entirely.
Attack and Defense stats scale by ratio, while IV and EV values are flat additions (43 points for a maxed out stat at level 100.).
Adding 43 to, say, Steelix' full IV, no EV or Nature 436 isn't going to make a huge difference in calculations, almost exactly a 10% difference in physical damage it takes, while adding 43 to Chansey's resting 46 nearly DOUBLES it's physical damage resistance. This is why pokemon like Chansey almost invariably get full EV investment in physical defense, it's just too good a deal to pass up.
It's also why pokemon with obscene base HP but paper defenses, like Wailord or Guzlord, should always split invest in their defenses instead of pile more onto HP to increase general bulk.
If they're even, HP tends to be the better investment purely because it does double-duty, but for pokemon with a big difference, investing in the lower stat generally helps more.
Nature boosts work by percentage, so those will have the same impact no matter how high or low the attacking or defending stat is, a flat 10% damage boost/reduction, excepting at very low stat values where the single point remainder can have a significant impact. Making either Steelix or Chansey have a defense boosting nature will result in roughly the same 10% physical damage reduction.
Speed and HP are the flat stats, where raw numbers matter, not ratios. Having a single point higher speed has the same impact as having double the opponents speed, except insofar as moves like Gyro Ball are concerned, or when you're trying to calculate if you still outspeed after a Scarf, Paralysis, ect.
This is also why Speed boosting natures on already fast pokemon are very valuable. You're actually getting more bang for your buck on them, versus the flat damage modifier the other stats give.
