It weakens all of those creatures until your next turn, so you can take advantage of their lower power so that you can attack on your turn, and then also benefit from the fact that your creatures cant attack as hard
Do make sure to note that Imposter Mech can only copy an opponents creature, which prevents crazy Sharuum, the Hegemon loops
Milotic V
Although it's unlikely to compete for the most valuable cards in the Scarlet & Violet era, this Gholdengo card offers unique artwork and is part of a two-card scene with its unevolved form, Gimmighoul
We don't recommend it, though, because it's janky as all hell - it's far easier just to hop over to your mobile browser and do it there
While the chances of this happening might be slim, since itd be a weird effect to reprint anywhere, its definitely not out of the question