Player pooling for younger ages might be a great way to scout, but for the older kids. There isn't anything prohibiting kids from any club to tryout and they will try and take the best that comes out. Could be a viva kid or a valor kid or someone from outside the union. It's just a name for the most part. The only place I've seen this actually work is PWSI and VSA to form VDA, even then it's not exclusively from those clubs.