Max Shutter speed
Olympus E-M5 III can shoot continuously at max speed of
30.0 fps and has max shutter speed of
1/8000 sec. E-M5 Mark III also has an electronic shutter which can shoot silently at max speed of
1/32000s. One thing to keep in mind is that electronic shutter may cause rolling shutter / jello effects, and also banding issues under artificial light on your images.
Flash
Unfortunately E-M5 Mark III doesn't have a built-in flash but it has a flash shoe for mounting external flashes.
Focusing
Olympus E-M5 III features both Contrast Detection and Phase Detection autofocus (AF) systems which ensures speed and accuracy of focusing in most situations. The AF system has 121 points to choose from. Olympus E-M5 III also features
Face detection AF where it intelligently detects the faces in the frame and locks the focus automatically.
Focus Stacking
Macro shooters will love Olympus E-M5 III's Focus Stacking feature. In this mode, E-M5 Mark III automatically composites multiple shots taken at different focal positions using focus bracketing to create a single image with maximum depth of field.