Holo
A holographic card is a shiny card with a black star, the picture is the shiny part of the card on a holographic card. These cards are often sought after and are technically 'more rare' than the reverse holo which is explained next.
Reverse Holo
A reverse holo is a shiny and black star except instead of the picture being shiny, the rest of the card excluding the picture is holographic.
Full Art/Full Body
Introduced during the Black & White Expansion, full art or full body cards have artwork over the entire card rather than just the tupper section of the card.
Secret Rare
Potentially the easiest card to distinguish despite being one of the hardest to pull from packs, a secret rare has a number beyond the cards in the pack. Check the bottom corner, if it's something like “120/110” it's a secret rare! These cards are often alternative art of cards which appear earlier in the pack.
Secret Rainbow Rare
Similar to a secret rare, this card number goes past the regular card numbers in a pack, but much like the name suggests, secret rainbow rare cards have a rainbow holographic across the card.
Gold Secret Rare
As above, the secret rare card refers to a card that appears past the usual numbers in a set, however the gold of this card refers to the holographic gold that coats the card.
Rainbow Rare
Appearing in the usual card numbers, Rainbow rares are known as they are as they have a distinct rainbow holographic artwork, this was introduced in the Sun & Moon Expansion.
Promo
Cards that are in promo sets, are cards that are part of a promotion or an event. These cards often have a black star with the word promo on top to distinguish them from regular sets.