Start playing with no cheats turned on. See if you can catch pokemon without crashing.I am having an issue where the game crashes when I encounter a pokemon in the wild. I had just updated the cheats to the 11/22 download. I am not sure which active cheat is the culprit. I am using 100% capture, Infinite Health, Infinite PP, items don't decrease, and 990 items when 1 used.
From there, add them back one by one until you figure out which one is causing the crashes.
Thats your best bet.