Quote from NihabaAshi:
Don't be confused because most traders don't use a mechanical trading system which might explain why most traders don't use C2 or the like.
Anyways, brokerage statements along with brokerage statements/testimonials by vendor clients or any trader should be suitable for situations where a trader isn't using a mechanical system...
However, nothing beats proof via watching any trader trade in front of your own two eyes in person.
Mark