Why hippoundon sucks in VGC.

Why is hippoundon bad in VGC:
Unlike singles this poke can't take any damage from anything else outside of what it's made to deal with.
VGC bases allot of calcs around mega kanga, mega salamence
Both these pokes are able to 2hko hippoundon with double edge , while he can only EQ back with a whisiny amout of damage.
Running enough investment to live 2 Returns from mega kanga would be taking too mutch away from needed offence and so on.
The poke's biggest lack imo is not being able to 2HKO mega mence with ice fang, Missing out on the KO with stone edge against thundurus.
Missing out on important KO's against many other things. It does however do a fine job walling mega meta.
It's special defence isn't too mutch of a flaw, outside of LO thunderus HP ice.

It's move pool is also a mess but can be switches out with ice fang(what does nothing outside of KOing lando with little to no investment.)
stone edge: does some more damage but i couldn't find any important KO's
Rockslide Picks up Important 2HKO's so ofc it run's that.
Earthquike, main stab, double hitting and with allot of investment it can 2hko mega meta.(poor damage output)
148 Atk Hippowdon Earthquake vs. 0 HP / 0 Def Mega Metagross: 78-92 (50.3 - 59.3%) -- guaranteed 2HKO




Rockslide + slack off + whirlwind + Earthquike.
why whirlwind? General pros and cons.
+ Resets any stat boosts gained, doesn't have to rely on catching them before they boost this includes evad boosts(--% acc).
+ Higher priority than Trick Room and bypassing Mental Herb(not too common to say the least)(cress run's it 11% of the times).
+ Forcing out a Pokemon can be useful in general if threatening.
+ Can tactically force out own Pokemon in a pinch (also a weird workaround Perish Trap by phazing your win con away :3).
- Won't work on the last two Pokemon.
- Negative priority also means that you are more susceptible to being targeted down before the move can be used.
- Can actually put you in a bad position if an even worst matchup possible gets forced in due to Roar.