Alright, I'll give a good core from a competitive point of view. Double Team is very gimmicky and doesn't actually guarantee a miss
Breloom @ Toxic Orb
Ability: Poison Heal
EVs: 252 HP/ 44 Atk/ 212 SpD
I present to you subseedpunch breloom. With leech seed and poison heal, you get a whopping 25% healed per turn! Special defense evs ensure that standard Starmie's surf does not break sub. Forus punch is a good STAB move behind a sub.
Metagross @ Choice Band
Ability: Clear Body
EVs: 252 Atk/ 252 Spe
- Meteor Mash
- Zen Headbutt
- Earthquake/ Trick/ Bullet Punch/ Thunder Punch
This guy hits REALLY hard. Last move depends on coverage/ strategy preference.
Here's a calc: Choice Band 252+ Atk Metagross Explosion vs 252 HP/252 Def+ Tyrantitar: 76.8-90.8%
Great choice of mons by the way. Their typings synergize very well.