I believe I can. I haven't done it before but you have to defog the area, save, change month, turn back on, something like that right?
I don't think I can do HP Fighting though because no matter how hard I try I can't find a spread for eggs or captures. I try searching 31/x/30/30/30/30 all the time and I get nothing. I'll keep looking. So far I have flawless, rock, ground, grass, electric, and fire. I have to research my Ice one cause I screwed up on it.