Rest of team: Haxorus Greninja Mega Manectric Snorlax Ferrothorn
I know I have two Grass types but please don't take that into matter when answering the question.
Use SHAYMIN-SKY. It has a amazing SpA and Speed, that let it to kill bulky Pokemon like Arceus and Kyogre and outspeed against some Choice Scarf users. And Serene Grace doubles the chance of flinching and dropping SpD harshly from Air Slash and Seed Flare to 40% and 80%. Immune to Entry hazard without SR. It has amazing moves, and after all a good Pokemon, and its in Uber. But due to its poor defensive stats, you need to use Healing Wish. When you foe will use a Ground type against Manectric, switch to Shaymin-Sky. It is immune to Breloom's Spore and can kill it quickly with single Air Slash.