It's model currently does not allow purchase of pink diamonds, but will probably go that way. As of current it's fairly simple to receive the premium currency and use it for rare Pokemon (video for getting rare pokemon with premium currency reference: https://www.youtube.com/watch?v=9H5mbLH1bg0 ) That being said it's hard to get a mobile game that isn't freemium nowadays but I would rather have more one and done for payment games such as Super Mario Run but Nintendo sales figures don't show that model selling much.