Currently, there are no items that improve Cutie's element score. The only stats the items can affect are:
Attack
Defense
Evasion
Luck
Drop Chance
Experience Boost
Raid Power
In addition to the common values of the items, they can give a "set buff" when multiple items from a set are equipped. Items that grant a set bonus have "Set x#" columns in their stat sheets. The # represents the number of set items needed to be equipped on the Cutie for that bonus to be applied.
Set bonus colums in an item page
Set bonus is not cumulative. The bonus is applied depending on the number of items equipped.
In addition to the set bonus, some items offer a Season Buff during Seasons and Events.
For more information on that refer to Season Buff article