STOP RUNNING 252 HP ON STUFF WITHOUT A THOUGHT. 252 hp corviknight reaches a quite beautiful clean 400 HP, but that's trash for a defogger really, because it is divisible by 8 (400 : 8 = 50 of course) which means stealth rock would deal exactly 50 HP of damage since corvi's neutral to rocks and thus take 1/8 hp of damage.
If you keep in mind that every fraction is
rounded down in pokèmon, if you just drop 8 evs from HP you still get an even number which means roost recovers exactly 50% but you actually take 1 less hp from stealth rock: (398 : 8 = 49.75, which means 49 because Pokémon don't want any of this .75 bs when calculating damage). This little tweak changes nothing with the Tapu Lele Psychic calc and even adds a bit more power into body press, however meaningless.
Also, if you really want it to, placing those 8 evs from HP to special defense, you actually get to live 2 shadowballs from specs pult from full hp. it aint happening since corvi is your defogger, but it still there and actually shows that
those 252 hp evs are actually completely pointless because you improve rolls on whatever side of defense you choose to place thos 8 evs, you won't lose anything relevant on the other side and you take less damage from rocks.

252 SpA Choice Specs Dragapult Shadow Ball vs. 244 HP / 96 SpD Corviknight: 168-198 (42.2 - 49.7%) -- guaranteed 3HKO
252 SpA Choice Specs Dragapult Shadow Ball vs. 252 HP / 88 SpD Corviknight: 169-201 (42.2 - 50.2%) -- 0.4% chance to 2HKO

252 SpA Choice Specs Tapu Lele Psychic vs. 252 HP / 88 SpD Corviknight in Psychic Terrain: 148-174 (37 - 43.5%) -- guaranteed 3HKO
252 SpA Choice Specs Tapu Lele Psychic vs. 244 HP / 96 SpD Corviknight in Psychic Terrain: 147-173 (36.9 - 43.4%) -- guaranteed 3HKO