Evolution Items

My understanding is that sunstone is the only item used in future gens.

In the main series, in addition to the current evolutions:
Sun Stone evolves Cottonee into Whimsicott (gen5), Petilil into Lilligant (gen5), and Helioptile into Heliolisk (gen6).

That is all that use the current items. I'm hoping that Niantic has some sense to reuse at least a few of these items. For example, reuse Upgrade to evolve Porygon2 into PorygonZ.

Im almost certtain they will be usefull in future gens because lots of mons needed to go to a certian zone to evolve in the game and im guessing thst will just switch to the evo items in this game

unless you already have a good kingdra, slowking etc. i don't see a point in having multiple stones that are not sun stones and even then it'll be a while till those are useful again

I like to keep a couple of each just in case I find a perfect or just really good pokemon that would need it. Not that any of those mons are exceedingly useful, but one or two of each item doesn't take up too much space in the item bag.