In the Sun & Moon era, the card had a lot of uses. Pikarom decks (Pikachu & Zekrom-GX) commonly used this, especially in earlier builds. This could set up for some big attacks or simply to get an Energy onto a Pokemon so it could retreat for free alongside Zeraora-GX. Decks using Naganadel could use it to fetch Energy and switch said Energy to another attacker, which was usually Blacephalon-GX. And really, while it wasn’t required or that common, any deck using a good amount of Basic Energy and had extra room could fit Energy Switch just to get an attack charged up later in a game when needed. Energy Switch was actually a very useful card for some decks, and almost reached staple status in those two decks above at some points. This was a very good era for a returning card.

illus. Ken Ikuji “Energy Switch” from Celestial Storm