There is a lot of really good suggestions online and on Reddit. What I thought was a really good few things to consider is - legendaries, mythical or any Pokemon that you only have a one chance encounter with and/or can't trade to get better stats. The other thing to think about is Pokemon to use for Master League PVP battles and Pokemon that have all three IVs sub 15 since allegedly there is code built in for regular bottle caps hopefully in the future. Golden is specifically for Pokemon that need all IVs boosted. Hope that helps!
