The only thing you have to do is form a cluster out of ALL plushies during the minigame once, and then save it in Autobuild.

The next time you play the game, just select the cluster, let the purple zone collect the plushies for you, hold the plushies over the cart, and exit the menu without actually “building” the cluster again. The loose plushies will fall into the cart.

That way, you won’t have to “ultrahand” them together every single time and/or drag single plushies to the cart.