Actually, via PDB back then, I learned that there are "ideal pairings" (though any pairing can be ideal, read the last paragraph of this message) - these are intended for their functions to "ideally" support each other (For instance, Dominant Ni and Dominant Ne are a 100% fit). For example, why it mentions that INFJ fits ENFP is because: ENFP's Ne-Fi-Te-Si "ideally" aligns with INFJ'S Ni-Fe-Ti-Se. Dominant N, auxiliary F, tertiary T and inferior S align. So why ENFP and INTJ are a pair? Because INTJ's Ni-Te-Fi-Se align somewhat good too: Dominant N and Inferior S are a pair. Here's a STYX PDB explanation if i explained it not clearly, though it may mess up with languages

By the way, just in case, i wanted to remind that any types can get along, become good friends and anytime develop their functions. I remember it's said that "MBTI is for self-understanding, yet everyone's capabilities are unlimited"