>>30588713This is objectively incorrect. Having more HP is usually better than having more of either defense because extra HP improves both your physical and special bulk, while PhD/SpD is split between the two. It's better to quantify a mon's bulk by simply multiplying its HP by either defense.
The main issue here is diminishing returns, applying to both HP and defenses. On one extreme you have something like Snorlax, with 461/166/256. You can get 127 extra point from EVs, up to 63 for each stat. If you get 63 extra HP both physical and special bulk are increased by 13%, but 63 extra defense gives you 37% increase in physical bulk. On the other you have Toxapex with 241/340/320 by default. You wished you could get all 508 EVs into HP for a delicious 52% overall increase in bulk, but you can only get 34% maximum with a mixed defensive spread.
Toxapex is still great thanks to Regenerator, Scald, Recover, Haze, Water/Poison typing and just enough raw defensive stats to make up for their bad spread. It's not like Regis which also have badly distributed bulk stats while being hampered by lack of recovery.