What's the minimum fall for a flat roof with edpm perpex polycarbonate
No, you have to follow manufacturer’s recommendations for fall.  And by the way, fall is discussed as a ratio of rise/run.  Nobody uses degrees for that; it’s an unwieldy unit that you have to keep converting in/out of.  Build some roofs; you’ll get it.
The reason for the fall is simply that an EPDM roof is a membrane. It is glued and sealed, and it could nearly be used as pool liner.
Whereas, “tin roof”, perspex etc. rely entirely on lap seams to keep rain out.  If the roof is too shallow, water will do an “S-curve” and run backward up the lap seam and get into the roof.