Pokemon gym holding Pokemon for 3 months

It is alright if you didn't put your main attacker in the gym.

get a second account. Niantic practically begs us to do that.

Do legendary raids with people, find people on a different team, then beg them to help you get that Pokémon out of the gym.

Or "cheat" by creating a new account, play it for a few days to get enough Pokémon to knock your Pokémon out of the gym, then do it.

The only way to get a Pokemon back is via battle. Or the extreme case is the gym gets removed. So the options are 1. Create a second account and kick your Pokemon out. 2. Ask someone of a different team to help.

Had the same Problem

It's finally a good thing that my family members all chose different teams (noob mistake at the time ;) No more stuck defenders (but never gym shaving).