HOW HAS NO ONE POSTED THIS YET?!
(All official smogon singles metagames except Little Cup, as well as monotype and 1v1)
TROLLPASS (Nosepass) @ Berry Juice
- Stealth Rock/Protect
- Magic Coat
- Pain Split
Turn 1: Use Stealth Rock. Sturdy will keep you alive and Berry Juice will bring you to full health.
Turn 2: If the opponent didn't attack you or you don't think they will attack you, use toxic. Otherwise, use Pain Split.
Until the opponent is at low health or faints: Keep using Pain Split.
When the opponent faints: Keep using pain split on the next Pokemon until they are at low health. Use toxic if given the opportunity.
When the opponent is at low health: Let Nosepass faint. Send out a Pokemon with a priority move, preferably also with moxie. If you think the opponent will switch out, use a stat-boosting move. Some Pokemon that fill this role are Mega Pinsir, Mega Scizor, and Bisharp.
Make sure to use Magic Coat against opposing status users.
Use Protect instead of Stealth Rock in 1v1. on turn 3 and onwards alternate between Pain Split and Protect.
Of course, this set isn't perfect. A lot of status users are immune to their own moves, and moves with a chance to inflict status will bypass Magic Coat altogether. You could also use a Level 2 Probopass to have an immunity to toxic.