Can you "Energy Trans" or "Dark Trance" a Rainbow Energy, Multi Energy, or any other special energy cards?
As long as they are providing the proper energy type and don't violate any other restrictions written on the card, then yes you may.
Source: PUI Rules Team (2004-05-06), PUI Rules Team (2005-11-17)

Relevant cards

Note: All applicable cards may not be listed below.
DP7_10
EX6_112
POP4_5