Okay, I know Dusk Balls have the best catch rate when used at night or in a cave, but does Primal Groudon's Desolate Land weather effect remove those conditions and make their catch rate only 1x?
No, if dusk balls aren't under darkness or in caves, then it has the same catch rate as an ultra ball
It depends what time of day it is, if its day time,the pokeball has the catch rate of a ultra ball,if its dark the duskball has a higher catch rate,
Hope this helps. Diamond :D