Personally I’d probably opt for a set with two top end (12″) and two subs (15″). A gym is not only rather widespread, but also high. Lots of places for the bass to get lost. I am afraid a “subless” setup will sound a bit on the thin side. IF you go for four top end speakers, you will need 4 stands, not 2.
Calculate a minimum of 10 Watt per person indoor (10 if you want it really loud). So 2x 1000W top end with 2x 1000W subs would easily have you cover about 400 pax, even in a larger room like that.
I’d scratch the fog machines. Get a hazer if they rent those, but be sure you start spreading haze early on. No hazer, then I wouldn’t bother.
Two lighting T-bars with 4 spots (LED) each would be a minimum. Preferably one of the newer generation ones with 3 or 4-in-one LEDs instead of 144 or so leds in various colors. In addition I would say two moving heads (smaller ones are fine, even LED if they are strong enough) or Moonflower like effects (check American DJ Revo 3 and 4 to see what I mean). The slimbanks (3×6 LED) look nice, you can use those to uplight some of the larger walls. Add two lighting stands (these are sturdier and rise higher than speakers stands). Finally some kind of lighting control, dmx controller with the necessary cables.
Be ready for the inevitable echo in a gym. Large, lots of reflective surfaces. Not much you can do about that, except hang big, heavy drapes on all the walls.
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