PPSE-DS HEX Editing

[Gowon]

I'm fairly new to this kind of editing and trying to figure some things out. I've found out that in Block 2 00-40 is the gender value, but when I change it from female (02) to male (00); its gender doesn't change when I go in-game. Also, when I saved a .pkm file of the edited pokemon and checked if it's legal, but it comes out to have an invalid gender. So do I have to edit other things with the gender for it to be "clean", like nature, and PID value? Plus, I did a little research about gender values and came by something about gender ratios of 1-127(female) and 128-255 (male), are these the values I have to exchange in Block 2 00-40?