When I level up, my opponents in the battle square are the other players. My friend, he told me that my opponent in the battle square was dependent on my level and some other information. So, he always keeps his level at 69 so he does not have to have stronger opponents. Only when he wins consecutive matches in the battle square, he meets stronger opponents. And so, he always has a high winning ratio. His frame is always over 5000 points. This is not fair.

why?

By keeping his level low, he is choosing to deny himself a tougher base for Lords mini-game.  (Due to lower level defenses). He chose to make the trade off.  I wanted the higher townhall 19 for the skill dmg reduction.

In choosing which heroes to improve you’re likely trying to maximize one mini-game over another with your resource investment, unless you’re “making it rain” by opening your wallet.  Your friend choosing to sacrifice one game mode over another is perfectly legitimate, imho.  (I would argue that most of the player base does this to one extent or another... I do really well in some areas and really poorly in others... because of the heroes I chose to invest have differing strengths.....)