Ok thanks for the answers but I found a way : I bred a female lapras with male slowpoke who had curse in Soulsilver, kept breeding until I got a male Lapras, then I taught it avalanche so that it has both curse and avalanche. Then I hatched female mudkip by breeding male swampert with ditto aka breeders best friend. Then I simply bred the male Lapras who had curse and avalanche with the female mudkip and voila, I got a mudkip with avalanche and curse.