HGSS - I imported Pokémon with the preferred hidden power and the move hidden power. I tested them on the elite four and it worked, I saved before facing lance as I usually do and I beat him. The end credit scene came on and completed, but then I got a file save corrupted message. I showed up back before facing lance and beat him again. I did it one more time and the same thing happened. So I took a guess and used tms on the Pokémon with hidden power and I saved. I beat him again and the game continued like it normally would. Idk if this is a known problem, but I thought I'd mention it to help out. I imported HP TMs and use them and did not get any problems afterwards.