What you need to do is get friends as low level as possible. As you raise through levels, keep looking for lower level friends. When you reach level 15, for example, you need a friend at level 5 or under, so your opponent sees all your players 180% or more. Then all your players are counted as 180% players against your current low level opponent. This is important, because otherwlse your better players overshadow this presumably lower overall percentage newcomer.

And where to find lower level friends? I think you should look from the market. Randomly go through bidders and when you find player with low enough level, send a friend request. And repeat this multiple times. You can't have too much friends in this game.