Do Primal EX-Pokemon count as Mega Evolved Pokemon? And will they take damage if the "Faded Town" Stadium is in play?
Yes. They have "Mega" printed on them, so they will receive 2 damage counters for Faded Town.
Source: Ancient Origins FAQ (2015-08-13), TPCi Rules Team (2015-08-13)

Relevant cards

Note: All applicable cards may not be listed below.
XY7_73