How to get celebi w\out gameshark or action replay
After your hall of fame debut, go to prof, oak and he will give you the G.S pass.go to vermilion port and you will see that the S.S anne is there again. Go aboard and battle two trainers. After that, someone will announce that the ship has docked in agate village. Go out and find the green-colored waterfall. There will be a Pokemon there. Go up to it and press A. It will make a battle cry and attack you. It will be at level 50 and it will be a celebi,. Make sure to bring lots of ultra balls. (approx. 80) MAKE SURE TO SAVE YOUR GAME B4 BATTLING IT, JUST IN CASE) then go back to the S.S Anne. Battle 2 trainers again and someone will announce that the ship is back at vermilion port.