I know this is a stupid question but what is gameshark & action replay?

Its not stupid. I didn't know until I bought one. Both hack into your gaming system and alter the game. Im not sure about Gameshark. Action Replay is where you enter codes and they do things like on my Pokemon Diamond I used some to get 100% Pokedex and shiny pokemon. On Animal Crossing I used it to get all gold stuff. Hoped this helped.

Cheat devices that alow you to do certian things. Ex: use a code that gives you all Pokemon, 999 rare candys, shiny Lugia, maxxed stats, all ribbons. Stuff like that.

They're both devices that allow you to enter codes, withwhich you can do the impossible on your game! (ex. Walk through walls, infinite items, etc.) There are different types for different consoles.

Its not stupid. We all have to learn sometime. And it's a cheat code thing pretty much. It already has cheats in it and you can also add new ones if you find some.

Yes that is sort of stupid because that is like the number one thing on this site that they always talk about. Game shark and Action replay are basically cheat systems meaning that they let you cheat. Basically you insert the gameshark into your Game Boy Adavance (SP) and then there is space in the game shark to put a game boy game. Then you turn on the game boy and a different screen will appear. That will be the game shark screen.It will show you different cheat such as in Pokemon one common cheat might
"unlimited master balls" or "unlimited stats on all pokemon". But beware it could mess up your game. Hope this helped!
NANOBOY25

No it isnt all they are is cheatdevices.