I noticed that some of the minions now have stats. But how do you raise these stats and what are they used for?

afaik you cant anymore..it was going to be for a minion battling thing in the past

the minion battle mini game thing is still accessible actually! if you go to your minion zoo and click the image of a minion that has stats, it'll take you to the mini game where you can battle and level up your minions

Thanks. It does indeed still work. :)