There is a way to gather RBY stats, just use the RBY stadium when battleing. The current stats aren't really significant, since most people don't use the stadium but here you see the current RBY top 20:
1,"128 - Tauros",29
2,"103 - Exeggutor",26
3,"143 - Snorlax",25
4,"113 - Chansey",24
5,"65...