For the sake of discussion, I am going to list everything below cutoff points, even BL mons, this does not mean BL mons are moving down.
4.36% to move either way this month, end of the season start of a new season.
Moving up to OU:
Jellicent
BL1 Mons below cutoff:
Lucario
Porygon-z
Haxorus
Moving down to UU:
Swampert
Gastrodon
Moving up to UU:
Electrode
Moving down to NU:
Slowbro
Typhlosion
Azumarill