In Cantonese, you can say 唔夾 to say A and B are not complementary. What's the equivalent in Mandarin?
不合 or 不搭?
'People being incompatible' is 唔夾 or 合唔來 in Cantonese and 合不來 or 不合 in Mandarin
These two people have always been incompatible with each other
'Things being incompatible' in Cantonese can also be 唔夾, and 不般配 in Mandarin.
Chinese medicine and Western medicine are incompatible
不合适，不般配， off the top of my head.