The new modified rules state you may only retreat once per turn. If you use a trainer to Switch your Pokémon, can you still retreat that Pokémon? Or does the Switch count as your one retreat per turn?
Switch does not count as your one retreat per turn. If it did affect it, I would imagine it being written as "(This counts as retreating your Pokémon)".
Source: PUI Rules Team (2004-06-03)

Relevant cards

Note: All applicable cards may not be listed below.
WOTCB1_95
WOTCB2_123
WOTCB2_123
BW1_104
BW7_135
DP1_119
DP3_128
DP7_93
EX1_92
EX11_102
EX15_83
EX6_102
HGSS1_102
SM1_132
SM1_160
SM35_67
SM7_147
SWSH1_183
SWSH1_183
TK4-Gyarados_28
TK4-Gyarados_28
TK4-Raichu_24
TK4-Raichu_24
TK6-Noivern_29
TK6-Sylveon_4
WOTCE1_157
XY0_38
XY12_88
XY5_163
XY6_91