Now that it's clear you're speaking of cognitive functions, I'm curious. Could you explain more about why you think ENFJ (Fe, Ni, Se, Ti) has the most potential for growth with an INFP (Fi, Ne, Si, Te)? What about an ENFJ with an ISTP (Ti, Se, Ni, Fe)?
I could say that "Ti suppresses Fe and Fi inspires it", but that would be begging the question. I could say "I am very sure that I am an INFJ, and I am very sure that I am more attracted to ENFPs than any other type" but you would have to take my word for it.
So ok, here's a theoretical explanation.
Take Te and Ti. Both of these functions work systematically. Te operates the system, Ti fixes the system. Te produces a thought, Ti checks that thoughts are consistent with each other. With just Te, you have something that works in practice but not necessarily in theory, and with Ti you have something that works in theory but not necessarily in practice. Ideally, you want something that works both in theory and in practice. You want to be doing things, but you want to make sure that you're not going to run into problems. Similarly with Fe and Fi. Fe mobilises people, Fi heals people. Fe produces an emotion, Fi helps bring about harmony between the emotions.
So, functions which share the same first letter but opposite second letters will both be working in the same domain, but will provide opposite sides of the process - and both sides are necessary.
We have, consciously, pairs of functions like Te and Fi, because that allows us to be balanced. We can work with systems/logic, and people/emotions. We can act, and we can reflect. But if you have a dominant Ti user with a dominant Fe user, the Ti will want to focus on the systematic aspect of something, and the Fe user will want to focus on the humanistic aspect. These don't work together too well. It's possible to get them to operate in harmony, yes, but it's more natural to have Ti working with Te, Fi working with Fe.
ENFJ's full function order is Fe - Ni - Se - Ti -- Fi - Ne - Si - Te. The gap between Ti and Fi is the crossing over from the conscious mind to the unconscious mind. It so happens that we have a tendency to associate our unconscious with another person. When we cross over to the unconscious, this has a connection to passing the baton to another person, a partner of interaction.
I'm still trying to work out how other relationships work, because I understand that we need all types to play some role in our life for maximum functionality. ISTP could be regarded as the worst pairing for ENFJ because it is the most suppressive to natural functioning, but even it has its time and place. Perhaps the ENFJ wants to work on its weaker conscious functions, to see them reflected in another person. I'm not sure if an ISTP is necessarily the best type for doing that, actually it would be probably better to have an INFJ and ISFP, but there must still be some proper place for it.
I am quite certain however that if you were to have only one other type to compliment your own, you would want to go with what I suggested. It is just the best, energetically speaking.