Say I attach a Water Energy to Eevee and do "Energy Evolution". I want to find a Glaceon but unfortunately I only have a Vaporeon in my deck. Do I have to attach the Vaporeon to Eevee?
No. Any search for a specific card or type of card in your deck can be "failed" at your option.
Source: Furious Fists FAQ (2014-08-28), TPCi Rules Team (2014-08-28)

Relevant cards

Note: All applicable cards may not be listed below.
XY3_80