See why the new gym system is going to benefit everyone now? CP is no longer a factor for getting a better spot in a gym. It's a FIFO system now (first in/first out). CP is still important for a Pokémon's overall HP and now those with higher CP are going to lose more motivation in battles as well as have a higher degradation rate of their motivation while staying in the gym. That provides balance for those who are at a low level and throw something in that's like around 1000 CP. Plus, no more low CPs on the bottom so even someone new to the game might get a longer time in a gym.
ALTHOUGH, my Flareon that WAS at the bottom of a gym lasted 149 days like that. I added another 133 day long reign of service to him (Feb 7 - Jun 19) to make a grand total and new name of 282 days!
Here's my new, improved, mostly powered up lineup (the 2 Rhydons underneath the 2800CP need more candy, but all my Eev-olutions, Gyarados, Snorlax, and all my battle worthy Exeggutors are fully powered up)
I also hope you all got your Ace Trainer badge where you'd like it too; with no more training it's a retired badge now.