I'm going to try out NU since I've only ever played OU and want something different. Here's my team so far:

Alo (Ampharos) @ Choice Specs
Trait: Static
EVs: 252 SAtk / 252 HP / 4 SDef
Modest Nature
- Volt Switch
- Thunderbolt
- Focus Blast
- Hidden Power [Fire]

Golurk @ Leftovers
Trait: No Guard
EVs: 252 Atk / 252 HP / 4 SDef
Adamant Nature
- DynamicPunch
- Stealth Rock
- Earthquake
- Ice Punch

Lickilicky @ Leftovers
Trait: Own Tempo
EVs: 252 SDef / 252 HP / 4 Atk
Careful Nature
- Dragon Tail
- Wish
- Body Slam
- Protect

Tangela @ Eviolite
Trait: Regenerator
EVs: 216 Def / 248 HP / 44 Spd
Bold Nature
- Leech Seed
- Giga Drain
- Synthesis
- Hidden Power [Ice]

Who else should I add? I'm completely stumped, as I've never played the tier. I've got a special attacker Ampharos who can take out Alomomola, physical attacker Golurk who can also wall Primeape and Sawk, physically defensive Tangela and specially defensive Lickilicky. I do know some of the top used Pokemon like Roselia, Musharna etc but I've no idea how to really play the tier.