About Power Struggles
How would you describe power to a pre-teen? One answer is "It is energy to create or change things." So a power struggle is a contest to see who can "get their way" (win) in a dispute. This can harm relationships and self-esteems, if it translates to "Who is better / stronger / smarter - you or me?"
This combative attitude promotes winners and losers, which can cause resentment, hurt, anger, guilt, and shame in the "loser" - specially if s/he is an unrecovering Grown Wounded Child (GWC). Shame-based ("egotistical") and fear-based people often initiate power struggles to "prove" to themselves and others that they are competent, worthy, independent (and maybe superior) people. Others do this to manipulate people.
A better alternative is win-win problem-solving, where each person strives to learn and fill everyone's primary needs equally, without resentment. In some vales conflicts respectfully agreeing to disagree is the best option. People who aren't able to choose these options consistently are probably dominated by a false self.