Design your own Level 10 Gym: Challenge
Okay we need ground rules to avoid 10 Snorlax
Rule1: Only 1 pokemon of any type
Rule2: List what Moveset Each has
Rule3: Assuming similiar levels/IVs so Order must be similiar to max CP order on pokemon. Max 250 CP Difference
https://pokemongo.gamepress.gg/pokemon-list-advanced
Example of Rule 3: You can have Vaporean above Gyarados in your gym because Vaps Max CP 3157 is within 250 of Gyarados max CP of 3281. But you can't put Lapras above Gyrados because Lapras's 2980+250 = 3230 and lower then Gyarados's max.
So even if you wanted Lapras farther up in your gym, someone with a higher CP Gyarados comes along and drops it in the Gym.
Answers
Nowadays with a good team everything is easy even if no one at the team has more than 2k cp if you time your dodges it will go down fast, that gym with a lapras for example (dragon + exxeg down), vaporeon (arcanine + rhydon down), good jolteon/raichu (slowbro+ poli down) and venusaur (gyarados+vape down). I think they should add something to make gyms a bit more difficult, for example reducing the cooldown for quick attacks on defenders