To my knowledge, there's been no counterfeiting of pokemon boxes. As to levels like with basketball... they don't exist. Every few months, a new "expansion" set comes out with new pokemon, different versions of existing pokemon (new attacks, hp, maybe different energy type) and new trainer/tool/stadium cards.
As you're new to pokemon, I'll give you some inside info. Premium rare cards (holofoil image, pokemon v, pokemon vmax, ultra rare and super rare) generally fall an average of 1 in every four packs. The ultra and super rates which feature full bleed etch foil are roughly 1 in every box. Do not confuse these with the holofoil parallels which fall one per pack. With the parallels, they don't cover the pokemon v, pokemon vmax, ultra rare or super rare cards. The odds with the parallels are roughly as follows - common 1:1, uncommon 1:4, rare 1:12, premium rare 1:36.
Finally, each set is broken down as follows - common, uncommon, rare and premium rare. These are spread over the following energy types - grass, fire, water, lightning, psychic, fighting, darkness, metal, dragon, fairy, colourless and trainer cards. Not every set will have dragon or fairy cards. Each pack contain 12 cards - 1 energy card, 1 pokemon internet card and 10 pokemon cards. Of the ten cards, you will receive 1 rare card, 2 uncommon cards 1 parallel and 6 common cards. The easy way to know if you'll be getting a premium rare card is to look at the internet code card - if the picture side is white, you have a premium rare of some kind which replaces a common. If it's green, no premium rare. Hope this helps.