Law and Kid has for sure devastating awakening powers but Luffy is even more devastating and he is a better user haki of all three colors. to be honest he can take on both of them at the same time and win. since he has future sight , he is faster than them , he can coat himself in ryuo and CoC haki.
they all fougt against Kaido , but Kaido never used FS against Law and Kid and he never used his full speed against them either.
they fought BM, who sure is strong, but too slow and doesn't have FS nor she uses CoC coating that much.