My vote will be
Species Clause. Why? For me, HO Spamming should vanish. Isn't healthy for the meta.
From the "Ban Guide" -> Dominant strategies with either no checks,
or the player has to choose between preparing for this specific strategy or the general meta
In teambuilding, for a good team,you must check a lot of threat, have a good defensive core (for balanced/stall team). You have maybe one or two check for one particuliar pokemon (like Yveltal for Gengar, Aegi/Slowbro for MMX) but is so hard to handle 4-5-6 of them, with some lure sets to kill the check and the HO win because you can't handle it with this pression.
Shell Smash isn't so hard to counter it, just some spam can be annoying. Also you got the bulk drop, you can scout easily that... Isn't the problem of HO spamming, I think.
Name Clause... Is like to prevent falling from cliffs you have two choices : a wall or just a brick. And you choose the brick. Doesn't solve the spam problems.
Shed could be a good suspect also, but i want to solve this HO spamming problem. A good Shed team is hard to play, necessite some skills, and HO spam not specially.