So the little brother and I went down to our local gym/pokestop location to train at the red gym and attempt to battle at the blue one, only to find someone had defeated the blue and left it unattended. We sprinted over to claim it and left a 581 Pincer (mine) and a 650 Flareon (his). Left it thinking that we'd get the critters back in 20 mins (it's a high turnover gym), however, half an hour later we've found that it's not only still ours, but also been levelled up twice. Good night all up I reckon
Also, I've noticed that the gym graphic changes depending on its level. At level 1, it'll just be the stage with a Pokemon on it, at level 2 there's a little mini stage in the tower/light beam thing. At 3 there's another and so on. The little stages also make it taller as can be seen in the picture
I wish there was some sort of "practice mode" where you can practice throwing Poke Balls at targets or something. I'm always hesitant to practice the curve balls when actually catching Pokemon because of wasted balls/risk of it fleeing, but would like to get better at it for the extra xp.
As an extension to this, daily minigames for xp/items is the logical next step imo.