I would agree it is a poorly-crafted English sentence. You can try breaking it down into phrases that you can understand. Once you do that, I think you will find there is only one meaning that makes sense. "These studios ..." we're talking about several studios mentioned earlier, perhaps movie or music studios. "... have also shown that ..." the studios are demonstrating something (also implies they are doing this again, for another time) "... all it takes for someone to stand her ground ..." somebody that we are talking about (a woman) has "stood her ground" meaning she is not surrendering to the pressure from others. This is related to the idiomatic expression: "She is making a stand." "... on what she knows is right ..." this woman has some fundamental beliefs (moral or ethical), some convictions she will not sacrifice. "... is for one other peer to join her." The reason being given for why this woman was able to withstand the pressures upon her against what her own moral/ethical beliefs of what is "right" were is that "one other peer" (that is, somebody else besides her) has joined her, agrees with her, stands by her side.

1. It is sometimes hard to "stand your ground" alone i.e. be strong in your beliefs or ideas, when you are challenged. 2. It is easier to "stand your ground" when someone like you (a "peer") supports you. 3. Sometimes, the support of one peer is enough for you to stand your ground. 4. In your example, this is what happened, and the studios showed this.