Gameshark is crap. It always stops working after like, three months or so. Maybe less. I don't really game anymore, so they're useless to me.
Both of my GameSharks still work. Well, the N64 'Shark only works every once in a while. It's broken. Literally broken.
Action Replay's exist in the U.S. Will, its how console gamers discovered the hot coffee mod existed on the PS2/Xbox as well .
That's weird. I was always under the impression that GameSharks were just called ActionReplays in other countries.
No. The only thing that I have to put into the GameShark is the actual game itself, but that's how it's supposed to work with the GameBoy 'Sharks. But maybe that's what you meant by "cards."