Jlrimages

In manual mode, flashes can be fired in one of two ways. You can attach pc sync cables from the camera to the flash, or you can use a wireless trigger. If you go wireless, then each flash needs either a receiver or an optical slave to fire the flash once it gets the signal from the trigger in the hotshoe of your camera. Some flashes have an optical slave built in - if not, you can buy a small attachment that has a slave cell in it. An optical slave reads the flash of a triggered light, and fires along with it.

If you are using speed lights as your lights, particularly when you are using lights from different manufacturers, it is worth it to invest in some basic, manual only triggers that have a hot shoe on them. That way you always have a method of connection if a speed light doesn't have a 3.5 mm jack or a pc port. I don't know much about the different Yongnou triggers and their comparability capabilities . But Phottix has some rock solid trigger/receiver units. So does Cactus. And the Cactus v6 triggers sync up to 1/1000 sec which is nice if you have a Fuji x-100 system which can sync at any shutter speed.

I haven't seen an EF-X500, but if there is a pc port or 3.5 mm jack port, you should be able to connect a pocket wizard to the flash. But since pocket wizards are manual only triggers, your settings are dependent upon the exposure you want. You'll need to meter the flash and set accordingly, or take test shots and adjust using the histogram. You need to shoot in manual mode, with shutter speed at or below the sync speed of the camera.

Aswald said "I guess, this issue exists with other formats too. Perhaps it is more significant as previously most medium format cameras rely on leaf shutters. Would HSS be a possible solution to this issue? Granted HSS itself has issues."
 
Yes, one of the significant differences between medium format and 35 mm based systems is almost total reliance on focal plane shutters in the 35 mm world. There are a few fixed lens cameras that use leaf shutters (Leica Q and Fuji x-100 series as an aps-c example), but all system cameras are focal plane shutter cameras. For them, HSS is the only option.
 
But, HSS is, at best, a partial solution. According to Profoto, their B1 strobe, which supports HSS, loses one stop of flash power for every stop above the flash sync you go. So, if you use the B1's HSS function with the Fuji, to get to 1/1000 sec from Fuji's 1/125 sync speed, you lose three stops of power. That just turned a 500 w/s strobe into a speedlight. By contrast, the Hasselblad X1D, can sync at 1/2000 sec with no loss of power. Yes, leaf shutter lenses are more expensive, but, lighting gear, especially lighting gear that is light and portable, is very expensive. So, for those photographers who use lighting gear on location, the cost of the leaf shutters are well worth the price. It's no more expensive for them, and it cuts down on the bulk that they have to carry on location.