i can tell you what i know.
hidden power is base on your genes. if you shark a hidden power different than what you currently have (why would you shark the same?) you WILL change your stats. the changes will take effect when you box & unbox your pokéys for sure, and possibly when you reload a saved game. (not sure of all the ways...)
anyway, try to keep with the high hex numbers for high stats, and keep as many bytes as you can an odd number for higher hp.
"what if mr. mewtwo has blizzard, perhaps the tm most commonly used on it?" - psybro teaching me humility
look, i'm a kiwi! (i'm in denial now... humor me...)