Yeah, just realised that Ice punch only does 50-58.85% to Zappy, which won't even KO after SR. Of course, Metagross does have Earthquake, so if Zapdos tries to roost, then it'll get KOd - but then it just becomes russian roulette between whether Zapdos is going to Heat Wave/ Roost, and whether Metagross chooses to EQ/ Ice punch. On the flip side, Ice punch would hit Lati@s harder, albeit at the expense of not being able to trap them.
The other alternative is to pump some more attack EVs into Meta and see what happens. I'll go have a play around with some calcs.
EDIT: Ok, so shuffling EVs around isn't really doing anything. I've just now started looking in to the Choice Band set, which is looking much more promising. Something like:
Metagross @Choice Band
Clear Body
Adamant - 252HP/ 252 Atk/ 4 Def
-Meteor Mash
-Bullet Punch
-Hammer Arm
-Zen Headbutt
I'm not even sure Ice punch is needed here; Zen Headbutt cleanly OHKOs Terrakion, and has a 31.25% chance to OHKO Zapdos after Stealth Rock. Likewise, Metagross only takes 26.64-31.31% from Stone Edge, meaning that it'll only get 3-4HKOd, as well as then giving Meta a free opportunity to launch a powerful attack in return (thus giving team 2 some pause before clicking Stone Edge/ X Scissor for Slowbro). Bullet Punch is nice too, as it gives team one some pretty powerful STAB priority, while Hammer arm rounds off coverage against the likes of Ferrothorn and friends.
The other alternative is to pump some more attack EVs into Meta and see what happens. I'll go have a play around with some calcs.
EDIT: Ok, so shuffling EVs around isn't really doing anything. I've just now started looking in to the Choice Band set, which is looking much more promising. Something like:

Metagross @Choice Band
Clear Body
Adamant - 252HP/ 252 Atk/ 4 Def
-Meteor Mash
-Bullet Punch
-Hammer Arm
-Zen Headbutt
I'm not even sure Ice punch is needed here; Zen Headbutt cleanly OHKOs Terrakion, and has a 31.25% chance to OHKO Zapdos after Stealth Rock. Likewise, Metagross only takes 26.64-31.31% from Stone Edge, meaning that it'll only get 3-4HKOd, as well as then giving Meta a free opportunity to launch a powerful attack in return (thus giving team 2 some pause before clicking Stone Edge/ X Scissor for Slowbro). Bullet Punch is nice too, as it gives team one some pretty powerful STAB priority, while Hammer arm rounds off coverage against the likes of Ferrothorn and friends.