I'd definitely have a bug type gym.
The gym itself would be located in a large hollow tree, much like the Fairy gym from gen 6 was. The tree would be littered with holes, bugs constantly flowing between them.
The inside walls of the gym seem to be constantly moving because of the many insects crawling around them. The main battle arena is a large platform held by Durants. The platform is covered in a sticky substance to keep the pokemon from falling off into the mass of writhing insects as the platform moves around the room, possibly even on the ceiling. As you made your way across this platform, trainers would drop from the walls and ceiling.
My costume would be a homage to Kamen Rider, pic related.
I'd probably be located as the fifth gym in the region.
Teams:
First Match:
>Lv 35 Yanmega - Speed Boost (Ancient Power, Air Cutter, Bug Buzz, Protect)>Lv 36 Durant - Truant (Entrainment, Iron Head, Crunch, Bug Bite)>Lv 39 Heracross - Guts (Close Combat, Rock Slide, Earthquake, X-Scissor)When Defeated, they'd get the TM for X-Scissor.
Rematch:
>Lv 73 Forretress @ Leftovers - Sturdy (Rapid Spin, Stealth Rock, Volt Switch, Gyro Ball)>Lv 75 Heracross @ Choice Scarf - Guts (Close Combat, Stone Edge, Earthquake, X-Scissor)>Lv 75 Volcarona @ Life Orb - Flame Body (Quiver Dance, Bug Buzz, Fiery Dance. Giga Drain) >Lv 76 Pinsir @ Pinsirite - Moxie (Swords Dance, Return, Close Combat, Quick Attack)>Lv 74 Shuckle - Contrary (Shell Smash, Power Trick, Stone Edge, Toxic)>Lv 74 Galvantula - Compoundeyes (Sticky Web, Bug Buzz, Thunder, Energy Ball)Against
>>19131322 I don't think I'd have that much trouble. I'd have to save Shuckle stall for Delphox though.
