[You Need a Thneed]

Originally Posted by Aegypticus

There's a slimy tactic some people use called "shaving". They'll have a second account on a different team that they use to knock down a gym of their own team just low enough to cut off the lowest Pokemon. They then prestige it back up on their real account and put their own Pokemon in. It's against the TOS and looked down upon by the community, but it still happens all the time.

Likely any gym where the lowest Pokemon out of 10 is 2800+ CP, I'd say it's nearly a certainty that this has happened.