Other known variants
x2Element ChainLook at the top 6 cards of your deck and attach any number of basic Energy cards you find there to your Pokémon in any way you like. Shuffle the other cards back into your deck.
Icy SnowThey are composed of ice crystals. They capture prey with chains of ice, freezing the prey at -148 degrees Fahrenheit.
Do I have to attach all of the Energy cards that I find using Cryogonal's "Element Chain" attack?
No. Since you are not revealing the cards to your opponent, you can choose not to attach any Energy cards if you don't want to and put them back into your deck.