Single post in Gym Forum Rules

I read through to see if there was an answer to my question but unfortunately couldn't find anything, what is allowed gimic wise? If I wanted to use the same pokemon (braviary to be specific) but train them differently enough to give them a challenge could I? Would I also be able to use deltas just to add some more variety to it so long as I allow challengers to use deltas? I thought it would be very fitting for a gym I run because of my hoard but if this isn't allowed I'll probably just do flying with a braviary as my ace