Depend tier list no longer important due to CP decay
Depend tier list no longer important people will just wait until the pokemon has very CP. Also moveset is longer important on defending pokemon
Attack tier list may also be longer important in attacking gyms due to cp decay. But is still useful in raids.
Answers
Waiting for decay is the sensible option.
It is not like it takes long...just do another gym and come back to the one you are waiting for.
Of course, this is more of a strategy for players who walk around with PoGo open not for those that drive around with Facebook, Gymhuntr, Discord and Twitter open.
...I guess we aren't supposed to walk around parks and walking trails with PoGo open anymore, instead we are supposed to drive to the nearest city and hang out in the city with everything other than PoGo active.