A person who acquires all mbti traits that he or she cannot decide about an specific mbti because he she can relate to every mbti sterotype.
In personality forums when you see a user with an unknown mbti it could be for two reasons: he doesn't know his type/confused about her type or......
He's a super mbti user.
Super mbti user is a very rare species. Probably only one out of millions acquire this trait. She's definitely a special snowflake or a super mbti user.
One clue if one is a legit super mbti user is that she can relate to everyone.

She has the equal balance of s and n, f and t, e and i.. Her right and left brain is perfectly balanced.

In cognitive functions terms, she possess both

Se and Ne,
Fi and Ti,
Fe and Fi,
Ne and Ni.

the thing that you don’t have when you’re phones percentage is over 20