Game Crashes at Giratina

Every time I go to fight giratina, I click on it, and my game crashes any suggestions? It says there was a script error.

Are you on 1.2.3?

Once I’ve downloaded the patch, how do I apply it?

Download patch, extract and then open that, open (1.2) core side by side, copy files from patch, and paste in 1.2 core.
Works for mac as well, same process just different UI.