Do people get along best with those of the same personality type? (MBTI)?

From what I've seen it is plausible that two people of the same mbti temperament would get along swimmingly. However, it ultimately depends on the individual people, as nobody perfectly fits any type.

Stereotypically speaking, you would be at the same wavelength as another ISTJ, assuming you guys have similar life experiences. ISTJ and ENFP are the reverses of each other, considering the order of their cognitive functions. The former has Si-Te-Fi-Ne, the latter has Ne-Fi-Te-Si. Think of each cognitive function as a state of mind. Having Si as your strongest function, you have an excellent capacity to store and recall information from your sensory database of the concrete, tangible aspects of the past. Your mind is adept at drawing out a map based on your impression of your experiences. The ENFP has Si as her weakest function, so she is much more prone to being scatterbrained, ditzy, and forgetful. You have Te as your second strongest function, making you skillful at applying logistical, step-by-step procedures to tackle challenges and reach goals. You generally trust established facts and tried-and-true methodologies of logic. The ENFP has Te as her second weakest function, so has a difficult time being organized and forming a structured mental checklist in her mind. She also has a bit of trouble with the implementation of logic.

On the flip side, you have Fi as your second weakest function, meaning that you have relative difficulty seeing past rules and expectations when forming personal value judgments. The ENFP has Fi as her second strongest function, bestowing upon her a fine sense of where she stands on moral issues, helping her readily identify her position on what is right and wrong, good and evil, etc. You have Ne as your weakest function. You have difficulty thinking outside the box, seeing possibilities that haven't already manifested, and utilizing abstract imagination. The ENFP has Ne as her strongest function, making her excellent at noticing what is missing from an environment. This gives her a quick, intellectual wit.

In regards to mbti, the letters mean virtually nothing. They really just tell you what functions a temperament has. It is the cognitive functions that matter. With that in mind, it could actually be said that the ISTJ has two opposite personalities: The ENFP, who has the same cognitive functions in the reverse order, and the ESTP who has the same preference order, but in the opposite orientation, and therefore, completely different cognitive functions. The ESTP has Se-Ti-Fe-Ni. The ISTJ is most likely inclined to perceive things similarly with an ESTJ (Te-Si-Ne-Fi).

All 16 mbti types are sensors, thinkers, feelers, and intuitives. The differences between them is in the order and orientation of such. I am not trying to say that the characteristics listed in the above paragraphs are true about you are particular. Those are just stereotypes based on the functions themselves.

Se = extraverted (objective) sensing
Si = introverted (subjective) sensing
Ne = extraverted (objective) intuition
Ni =introverted (subjective) intuition
Te = extraverted (objective) thinking
Ti= introverted (subjective) thinking
Fe = extraverted (objective) feeling
Fi =introverted (subjective) feeling

For a relatively simple description of the cognitive functions, look for my responses: https://answers.yahoo.com/question/index?qid=20141015142032AA2ra9O https://answers.yahoo.com/question/index?qid=20130824143411AAOV3Wi (ignore irrelevant info)

I think sensors get the best along with other sensors, and intuitives with other intuitives. Opposite E/I, T/F and J/P don't really matter as much in my opinion, but with sensing and intuition there will probably be a communication gap. People say that opposites who share sensing or intuition are very compatiable, as they kinda complement each other, I guess. ENTPs and INFJs are supposed to be a perfect match.

Opposites