>>542547454
Aside from new skill books in the monthly shop, there are events every half/anni where you can buy extra stuff with friend points.
Clovers are mainly for the monthly tickets but you can also use them for the weather and starting post items, good for LoH.
Parfaits are always useful for getting your weekly stadium high score and for the occasional guaranteed box opponent. They are also required for LoH.
Glitters are used to upgrade starting skill hints, around 270 to max upgrade all per uma.