I used to use gengar with hypnosis and dream eater to cycle through them. But what's the new go to Pokémon with move set to catch em?

LVL 100 Smeargle might be good, can learn most moves because of sketch

Spore/Dark Void (put to sleep) (Spore has 100% accuracy but does not hit grass types and overcoat ability)
False swipe (Leaves them at 1HP unless they have recovery or rest)
Mean Look (prevents roaming leg. just running after 1st turn)
Sword Dance/Taunt/Foresight (Boost up against rock/steel/Ghost types to guarantee false swipe knocking them down to 1HP)

I personally use a drain life false swipe Spore Breloom to catch shit with, he doesn't died, can status and bring them down to 1hp it's absolutely perfect for a legendary or even all around catching pkm just my opinion.

Id day paralyse and false swipe
Mean look if it can run away

Sleep isnt permanent, paralysis is

Burn and psn too ofc, but u can kill 'em woth it

sleep means they literally cant do anything for 1-3 turns and you can do anything, paralysis is a close second with the chance of 20% to fully para in S&M and lowers speed but legendaries can still boost up, rest, or atk.
sleep is so broken that smogon had to make a rule called the sleep clause.