Iono is a very useful card against decks that rely on discarding hand cards, like Gholdengo whose main attack is discarding energy for a 50hp hit.
It's useful in decks to completely reset your hand, but also if you're close to losing, the disruption of the opponents hand may just be enough of a lifeline to strike back.
Good post, thank you for sharing!
I play a bit with Gholdengo decks. Iono does hurt Gholdengo players and decks that have massive hands like Chien-Pao, Lost Zone Giratina, etc.
Hand disruption in Iono is quite powerful. A Gardevoir ex player could play Iono when the opponent has 1 prize card remaining and do a (massive) comeback win.