http://www.smogon.com/forums/threads/usage-based-tier-update-for-september-2017.3614028/

Gardevoir-Mega moved from OU to UU
Jirachi moved from OU to UU
Machamp moved from NU to RU
Banette-Mega moved from UU to RU
Moltres moved from BL3 to RU
Kingdra moved from BL3 to OU
Nihilego moved from OU to UU
Mantine moved from RU to UU
Gallade-Mega moved from OU to UU
Tornadus moved from UU to RU
Hawlucha moved from UU to OU
Ampharos-Mega moved from OU to UU
Latias-Mega moved from OU to UU
Manaphy moved from BL to OU
Heracross-Mega moved from OU to UU
Drapion moved from NU to RU
Abomasnow-Mega moved from UU to RU
Decidueye moved from UU to RU
Meloetta moved from BL3 to RU
Dragonite moved from BL to OU
Absol-Mega moved from UU to RU
Altaria-Mega moved from OU to UU
Ninetales-Alola moved from UU to OU
Quagsire moved from NU to RU
Froslass moved from RU to NU
Smeargle moved from OU to UU
Manectric-Mega moved from OU to UU
Camerupt-Mega moved from UU to RU
Heracross moved from BL2 to UU
Nidoqueen moved from UU to RU
Audino-Mega moved from RU to NU
Hoopa-Unbound moved from OU to UU
Rotom-Wash moved from OU to UU
Tsareena moved from UU to RU
Zygarde-10% moved from UU to RU

Lots of changes this time, discuss.