An energy is a card that you attach to Pokèmon to get them to attack. There are lots of different sorts of energy. Some are called basic energy which are normal energy cards which only give out one of one type. Here are all of them:

Fire Energy

Water Energy

Grass Energy

Lightning Energy

Fairy Energy

Dark Energy

Fighting Energy

Metal Energy

Psychic Energy

There are other energy cards called special energy cards. You can only have 4 of these in your deak. Here are some of them:

Double Colourless Energy

Rainbow Energy

Double Dragon Energy

Prism Energy

Plasma Energy

Herbal Energy

Strong Energy

Mystery Energy

Shield Energy

Wounder Energy

Double Aqua Energy

Double Magma Energy

Flash Energy

Dangerous Energy

Burning Energy

Rayquaza EX

This card is Rayquaza-EX. Look at the good energys to attach, the energy cards needed in the attack cost and The different thing about dragon type.

Dragon type is different from the other types because dragon Pokémon need two different types of basic energy in their attack costs.

Colorless energy symbols in attack costs mean you can attach any sort of energy and other symbols (let's say fire for instance) mean you can only attach an energy of their type.