Attacks » Push Down
If Sawsbuck attacks with "Push Down", who chooses which benched Pokemon to make active?
It says "your opponent switches", so the defending player chooses.
Source: Emerging Powers FAQ (2011-09-01), PUI Rules Team (2011-09-01)

Relevant cards

Note: All applicable cards may not be listed below.
BW2_16
PL2_64
POP9_14
XY3_86
SWSH5_16
SWSH5_16