ok if u want to get the cheats to work you have togo to cheats and it have codebreaker
gameshark code and choose wich 1 u 1ant

you catch latias in the wild(its rare)to catch it use ur master ball.if you already used
it on rayquaza,weaken to below half its hp.and keep throwing ultra balls at it.use block
or mean look on it so it wont fled like it always does when you encounter it.theres
another thing u could do.hack uing ur game shark.srry my answer is soo long.just have one
more thing to tell ya.u can find a master ballin team aquas or magmas hide out.sorry again
idk the code for the free master balls.i hoped i helped.sorry one more time for the really
really really long read.

how to get latias:
1.use repel
2.go to the upper side of slateport (cycling road)
3.use acro bike then jump on a grass
4.then wait.....if doesnt work go in the cycling road then out again.do 1-3 again
(i have 30 latias,rayquaza,kyogre,groudon all lvl 100)