I'd say all of the rules in my gym are also present in many other gyms. No IBJJF rule limits, bowing on/off, being clean, any gi that's not torn up can be worn etc.
However, there is one practice that has unofficially come about that may be unique to my gym and it has to do with my deafness.
I call it the "3 second pause".
When I spar or drill something that has to do with the head, I take my hearing aids off and stick them someplace safe. After that, if the instructor or someone else wants to talk to me in anything more than a short phrase I can lip-read, I need to go get my hearing aids and put them back on.
However, the wizards who built my ear pieces put an unalterable five second delay between the turning on of the hearing aid and the delivery of amplified sound to my ears. Apparently, old people complained like crazy about wanting to push the button and have a delay so they can take their own sweet time plugging them into their ears. And the wizards believed that this was smart or at least what the majority wanted and they made it so.
Anyways, I say "Hang on", dash to the safe spot, snap the hearing aids on, plug them into my ears and go back to the instructor or other person.
And we wait for 3 seconds while my ears boot up. Everybody willingly accepts this pause and will use it to adjust belts, look around or just zone out for a second. They're so patient for that time to elapse and for me to say "Okay".
Then class resumes.
So the gym has a 3 second pause rule while my ears boot up. That's pretty unique.