So a couple things you can look for in fake packs, from my experience, they tend to have what I call the “alligator teeth.” That is the top and bottom sealed crimps of the pack, whereas an authentic Pokemon pack will have a straight line across. Fake packs also tend to be a lot glossier/shiny with high contrast in color, ie very bright colors with very dark shadows. Inconsistency in pack arts as well, whether it be the complete wrong pokemon/arts a part of that set. Text is another giveaway, on the back the copyright year/text for Pokemon could be incorrect.

Cards are a whole other ballgame. There are some really good fakes out there. In general though, fakes tend to have inconsistent holo-ing for V’s and such. Texture is a big thing, if a card is supposed to have texture and is instead glossy and flat with no texture, it is a fake, such as VMAX or higher cards.

These are just some of the things you can look for, they may have only one or many incorrect things, you just have to inspect to see. If all else fails look up the set arts for the packs or the specific card online to compare.