Let’s say 3 defense team slots are provided for raids, wars and tournaments. You can set 3 defense teams with ‘different color’ tanks. One of your defense teams is randomly selected at each time the enemy picks you in raids or tournaments, or at the beginning of wars.
This way, even if one tank hero is way too dominant, you can only see her/him 33% of the times.
I think it’s also a good way to solve the Telly problem without nerfing her.