There’s some merit to pickle juice helping when you’re already suffering muscle cramps, but it’s believed to have more to do with the body’s response to the acidity than the actual electrolytes in it. Coconut water beats pickle juice, in terms of electrolytes and real rehydration, no question.
With the volume of activity she has (which sounds just a little crazy. Just sayin’), I’d say skip the BCAAs and get her some protein and carbs. With all that playing time, it’s not only electrolytes she needs, it’s basic calories. Finibars were designed to be eaten during competitions while being super-easy to digest and light on the stomach. I’d go with those between periods and/or between games, along with plenty of water.
Coconut water is great, but it’s very easy to overdo potassium because it’s such a concentrated source, and potassium in high doses can have a laxative effect. That’s, um, not something an athlete needs to deal with in the middle of a game.