What happens if I attach a Rainbow Energy to Roserade with the "Energy Signal" Poke-POWER? Do I get to use both effects?
If the Energy card you attached provides all types (for example, Rainbow Energy), then both effects would trigger. Energy Signal would both Confuse and Poison the Defending Pokemon.
Source: PUI Rules Team (2010-09-30)

Relevant cards

Note: All applicable cards may not be listed below.
HGSS1_104
HGSS2_23
PL1_121