Items on a holder

Your items usually come before your carry. Components drop from the first rounds on, while the unit your comp is built around may not show up until much later, or not at two stars until you roll for it. Hold the components all that time and you play the early game with no items at all.

So put the items on a holder: a unit you already field that deals the same kind of damage as the carry you are building toward. The items work from today, and the holder wins you rounds while you wait. Pick the holder by damage type, and the same items fit both units, so nothing is wasted when they move.

When the carry arrives, move the items. Selling a unit returns its items to your bench, so the swap costs you the holder and nothing else. Move the items once the carry would do more with them than the holder does: usually when it reaches two stars, or at the roll down where you expect to find the copies. A 1-star carry with the items is not always stronger than a 2-star holder. A carry fielded while another unit keeps its damage items is a carry doing nothing, and the game review flags it.

Tanks work the same way: a cheap frontline unit can hold the defensive items until the real tank shows up. Either way, give the holder only items the unit taking over will use. A unit holds 3 items, and every one of them should still be right after the move.