Can I use Murkrow's "Switcheroo" attack to move an opponent's "Energy Gain" to a non-SP Pokemon?
Yes you can, but if the Pokemon you move the Energy Gain to is not a Pokemon-SP then the tool would be discarded after it gets moved.
Source: PUI Rules Team (2010-11-18)

Relevant cards

Note: All applicable cards may not be listed below.
DP4_43
PL3_72