Your average to low CP pokemon can takedown a high CP gym easily. Might not be able to hold it but taking it is easy. You use 6 pokemon to battle and can heal as much as you want. You can also get others to help you fight the gym at the same time as you making it even easier. The idea is to get lots of low level players to compete against one or two high level players, the sense of victory and teamwork is the reward.Pokemon go makes me sad
Finally hit level 6 this morning.
then caught 4 more new pokemon.
Have 13 balls left, no pokestops anywhere I can get to (without really going out of my way) and the only gym near to us has a very evolved owner at the moment.
So yea, will not get far with this game.

