In the last few weeks, I've abandoned the 1-troop defense in order to field event troops and help out my fellow players.
During that same time, I amassed my longest win streak ever - more than 500 wins more than my previous win streak that I got when I was about level 200.
Several hundred of those wins were against Wraith / Courage / Bone Dragon combos. Wraith is easy to beat, there's nothing about him that makes him "impossible". Bone Dragon is easy to beat.
It's about these troops having powers that are well above and beyond other troops of their base rarity, which in turn makes them over-prevalent in the defense meta.
Let me repeat - ALL troops in this game are easy to beat. There isn't one troop that isn't. But there are 5 or 6 troops that appear in EVERY PVP match offered and that's not healthy for the game. That is why Wraith needs nerfed. That is why Bone Dragon needs nerfed.