I've been working on a Mega Metagross team lately as it seems to be one of the megas i enjoy using the most lately. This is a Doubles team by the way
Mega Metagross @Metagrossite
Nature: Jolly
EVs: 252 Attack, 252 Speed, 4 HP ((I have been thinking about a more bulky spread but i'm not sure i want it))
Moves:
-Protect
-Substitue
-Iron Head
Zen Headbutt
Obviously the mega of the team. The EV spread is simple as i'm more or less trying to nail down the team synergy right now more than optimizing the EV spread. Substitue is a new addition to Metagross. I was running Ice Punch on Metagross and to be honest, i think i actually like the added coverage Ice Punch gives. Substitue was suggested by a friend but i'm just not sure how much i like it.
Hydreigon
Life Orb
Nature: Timid
EVs: 252 Spattack, 252 Speed, 4 HP
Moves:
-Dark Pulse
-Draco Meteor
-Flamethrower
-Earth Power
Fairly standard Hydreigon set here, not much to say. It compliments Metagross very well since they cover each other's weaknesses.
Conckeldur @ Assault Vest
Nature: Adamant
EVs: 252 Attack, 136 Def, 116 Spdef
Moves:
-Mach Punch
-Drain Punch
-Ice Punch
-Knock Off
This set was mainly designed around the fact that i don't have Ice Punch on Metagross. The 136 Def EVs gives me 132 base defense, 116 Spdef combine with Assault Vest gives Conk a over all 150 spdef. The 252 Attack EV's gives Conk max attack in order to hit things like Thundurus and Lando-T super hard. However, what i have noticed with this set is that i feel like i'm taking to much damage on the physical end. If i end up switching back to Ice Punch on Metagross i may switch this to a more bulky spread. Say close to max HP with about with minimal attack investment, enough to hit about 180 attack.
Milotic @ Leftovers
Nature: Bold
EVs: 252 HP, 252 Def, 4 Spattack
Moves:
-Recover
-Icy Wind
-Scald
-Ice Beam
Normally i would run Suicune as my water type but with Sitrus Berry being taken, i wanted to use something that could heal itself if needed. One option i had considered was using Rocky Helmet in place of Leftovers so that i could lead Metagross plus Milotic against Kang leads and force the Fakeout onto Milotic to grab some extra damage on Kang while setting up a sub turn two to avoid Sucker punches while Milo fishes for a burn.
Zapdos @ Sitrus Berry
Nature: Modest
EVs: 252 HP, 72 Def, 36 Spattack, 88 spdef, 60 Speed
Moves:
-Tailwind
-Roost
-Thunderbolt
-Hidden Power Ice
I wanted to give something else a try instead of Suicune for Tailwind support. I've heard Zapdos is a pretty good Tailwind user and it hits like a truck even without to much special attack investment. 60 Speed EV's gets Zapdos up to 128 base speed, which is one point higher than my Rotom-H and i wanted to know exactly which would go first if there were both on the field at the same time. The other reason why i wanted Zapdos instead of Suicune was because of Talonflame. Talonflame is a real issue for Metagross so having a check to it was important to me. While Milo checks Talonflame and many other fire type pokemon, it often doesn't OHKO talonflame, so the chance of a Flare Blitz coming on on Metagross was still there. Zapdos solved this issue being able to OHKO Talonflame a majority of the time. The only time it wouldn't OHKO Talonflame was if the opponent was running a max hp and max spdef Talonflame, which is unlikely to do a ton of damage to Metagross anyways. This same logic was also applied to Mega Char Y as it is a issue too.
Rotom-H @ Safety Goggles
Nature:Modest
EVs: 92 HP, 252 Spattack, 164 speed
-Protect
-Will-O-Wisp
-Overheat
-Thunderbolt
As mentioned above, i wanted something that could deal with Talonflame, not only this but i wanted something that could deal with Char-y behind a Amoonguss redirection. Rotom-H does this for me. While it doesn't OHKO Char-y, it does do about 90% to a bulkyish Char-Y, so in two turns it can take care of Char-Y allowing Metagross to come in and start mopping up.