Hi I used the action replay to get to birth island to catch deoxys..

Here are the instructions
1. Start at the bottom Press A
2. Go down one step and then all the way to the left Press A
3. 3 steps right and go all the way up Press A
4. 5 steps down and go all the way to the right Press A
5. 3 steps up and go all the way left Press A
6. Go all the way to the right Press A
7. Go three steps left and face down
8. I would highly reccomend to save your game. Press A

You have to get the triangle to the center. You do this by hitting it at different angles you'll know you are doing it right when it starts going to different spots other than the three corners.

There is a complicated way, but you can find instructions on how to turn it into deoxys in the fire red cheats. It also works on emerald. Hope I helped , Groudon Dude.

It's tricky, but if the other answer doesn't work for you, try looking a page or so back b/c I just put them there 2 times about 10 days-2 weeks ago. They are the exact ones from Nintendo, and worked fine for me!!
Just don't TOUCH the triangle-only go close to it or it'll restart you at the beginning of the puzzle.
Good Luck!