All of the tier shifts that would have happened in January with the usual cutoffs:

Diancie from UU to OU
Sceptile from RU to OU
Tentacruel from UU to OU
Politoed from PU to OU
Pinsir from OU to UU
Heracross from OU to UU
Salamence from OU to UU
Gligar from RU to UU
Pidgeot from RU to UU
Whimsicott from RU to UU
Kingdra from UU to RU
Accelgor from NU to RU
Abomasnow from RU to NU
Skuntank from RU to NU
Virizion from RU to NU
Banette from RU to NU
Emboar from RU to NU
Kecleon from PU to NU
Musharna from BL4 to NU
Scyther from PU to NU
Probopass from NU to PU
Torkoal from NU to PU
Armaldo from NU to PU
Samurott from NU to PU
Pawniard from NU to PU