How do I stop Pokemon Ultra Moon from crashing on 3ds?

Hi there! My Pokemon Ultramoon keeps crashing at very random times on my 3ds. My 3ds has CFW that's up to date. Right now I'm using the homebrew ROM as Nintendo e shop won't work at all on my device. I did use PK Hex to get some event Pokemon in my game, as well as mod some Pokemon I've caught. I made sure the Pokemon passed there PK Hex legality check.

Has anyone else had similar trouble with Ultra Moon? Is there any fix? Should I try getting the game from a different source?

Thanks for the assistance.