my friend http://the-cavern-gied.deviantart.com/ did this http://chzpokememes.files.wordpress.com/2011/11/pokmon-create-your-gym.jpg and it seemed fun so i'll give it a shot.
Type: Grass
Pokemon: Cradily, Abomasnow, Simisage, Cherubi, Exeggcute
Rematch team: Bellossom, Maractus, Leavanny, Tangrowth, Sceptile, Venusaur
Gym: Forest themed, pokemon trainers hide in long grass or are hidden against tress. you need the HM cut to be able to progress through the gym, fairly straight forward path to the Gym leader, but many battles in the gym are unavoidable. It is impossible to leave the Gym with defeating the gym leader or being defeated yourse