Hi - first of all, you will never be able to build a defence team that prevents loss of trophies. Every defence team can be beaten. For your current roster, I would level Kashhrek and Boril and Rigard and Gormek and Wu Kong until you get a better yellow defence hero. My opinion is that a Rainbow defence team is best. Good luck
Yes - Wu Kong is better on attack rather than defence. However, you are better with a rainbow team in defence, and I can’t see another 4* yellow. You could try Bane for a while …