Here's something I posted a long time ago in response to someone suggesting the idea of Ambiversion, and why I think it's very confusing:
If you want me to offer my version of this, I guess I'll play too. Presuming I believed in dynamic type (which I am not saying I do one way or the other, I'm just accepting the assumption for the purposes of description), this is how I would go:
I/A/E (Introverted, Ambiverted, Extraverted)
N/R/S (iNtuitive, Realist, Sensor)
F/B/T (Feeling, Balanced, Thinking)
J/M/P (Judging, Malleable, Perceiving)
Thus (as examples using I-N-F-J as the potential statics in each position, and assuming Dominant, Auxiliary, Tertiary, Inferior ordering):
ARBM -- Xx, Xx, Xx, Xx (Everything is subject to change completely, although the functions are in an unknowable specific pattern at any given moment. Worst case scenario.)
IRBM -- Xi, Xe, Xi, Xe (Well, the I/E is static... everything else is dynamic.)
INBM -- Xi, Xe [N], Xi, Xe (We know one in the first block is N, and one in the second block is S, but we don't know what kind or where... and it can change.)
INFM -- Xi, Xe [NF], Xi Xe [ST] (We now know this is an INF with an EST shadow. However, the functions are subject to change, except that the first block contains some form of Feeling and Intuition, and the second block contains some form of Thinking and Sensing.)
ARBJ -- Xx, Xx [Je Pi], Xx, Xx [Ji Pe] (We only know that this type has Extraverted Judgment and Introverted perception in the first block, and Introverted Judgment and Extroverted perception in the second block.)
IRBJ -- Pi, Je, Ji, Pe (This is an IJ type. They use some form of Introverted perception as a dominant function, and some form of Extroverted Judgment as an Auxiliary. The specifics are subject to change.)
INBJ -- Ni, Je, Ji, Se (This is an INJ type. They use Ni and have inferior Se, and use some kind of Aux. Extroverted judgement and Tertiary Introverted Judgment that is subject to change.
ARFJ -- Xx, Xx [Fe] Xx, Xx [Ti]. (This type uses Fe in the first block and has a Ti shadow somewhere in the second block, however the specific location and accompanying functions are subject to change.)
IRFJ -- Pi Fe Ti Pe (This is an IFJ type. They have some Introverted perception as dominant, Fe auxiliary and Ti tertiary, and then Extraverted perception as a shadow.)
ANFJ -- Xx, Xx [Ni Fe] Xx, Xx [Ti Se] (This is an NFJ type. They have either Ni or Fe as dominant, and the other as auxiliary, but which is subject to change. The same applies to their shadow.)
ANBM -- Xx, Xx [N] Xx, Xx (I/E not static, otherwise same as INBM.)
ARFM -- Xx, Xx [F] Xx, Xx [T] (J/P not static, otherwise same as ARFJ. Somewhere in first block is Fe or Fi, somewhere in second is Ti or Te. Exact position subject to change.)
Anyway, this should give you an idea of what we've opened up here with permitting dynamic type... we need to use these models to figure out which functions are possible for each position with each letter of certainty. I don't want to try it with every letter combination, of course.
This complexity, unfortunately, does not mean such dynamic type isn't the case, however. Some people may have significantly higher degrees of neuroplasticity than others, and this may be the best they can do.
Do you see how annoyingly complicated this makes things?