Is this pokemon hacked?

This has been bothering me for a long time now. I own a pokemon emerald game. I know that you could get mew from an event in Japan that has sadly long since ped. I was wondering would it be considered hacking if I used my gameshark to just get to the island where mew is, the remove the gameshark and refresh entail I encounter a shiny mew? This is on my English pokemon emerald.