[REQUEST] Can you competitive geniuses out there help me?

[P35]

Hey guys! Can you give me advice on my defensive toxapex?
im not sure if I should run regenerator or merciless. I'm also not sure on the moveset.
Here's what I have so far:
Bold 
Evs- 252 hp 252 def(maybe sdef) 4 speed
recover
toxic 
haze
???
almost perfect ivs 

Any advice for the fourth move or just in general? Thanks in advance