Pokémon Reversal forces a coin-flip repositioning swap on the opponent's side. The Expedition wording had the player choose one of the opponent's Benched Pokémon and, on heads, switch it with the Defending Pokémon. Ruby and Sapphire's rewrite handed the switch to the opponent, who picked which of their own Active and Benched Pokémon traded places; an errata later made it play more like the Expedition card, with a small adjustment for 2-on-2 play. The FireRed and LeafGreen wording reflects that: the player picks the Benched Pokémon and the opponent picks which Defending Pokémon leaves. HeartGold SoulSilver simply swaps the chosen Benched Pokémon with the opponent's Active Pokémon.
The card first appeared in the WOTC era in Expedition Base Set, then returned across three EX era sets, Ruby and Sapphire, FireRed and LeafGreen, and Unseen Forces, each of those three illustrated by Hiromichi Sugiyama. Its fifth printing came in HeartGold SoulSilver with new artwork by Wataru Kawahara. Our catalog lists 5 printings.
The HeartGold SoulSilver wording ended up matching the errata'd effect of Pokémon Catcher, a card later released in Emerging Powers. Before its official English release in Expedition, the card first appeared in the Japanese Pokémon VS expansion and in an unofficial English Tyranitar Half Deck made for the 2001 Tropical Mega Battle, where it carried the tentative name Pokémon Reverse.
The Expedition Base Set printing is the card's first official English release, letting the player pick the opponent's Benched Pokémon to swap in on heads
The Ruby and Sapphire printing introduced the reworded effect that was later reined in by an errata
The HeartGold SoulSilver printing carries new artwork by Wataru Kawahara and an effect that matches Pokémon Catcher's errata
The card has four distinct wordings across its five printings, spanning Expedition through HeartGold SoulSilver.
Its rewritten text let the opponent choose how to switch their own Pokémon, which Bulbapedia likens to turning a coin-flip Gust of Wind into half a Warp Point; the errata made it play more like the Expedition print, with a tweak for 2-on-2 play.
From Expedition Base Set (2002) · 1 printing
Choose 1 of your opponent's Benched Pokémon. Flip a coin. If heads, switch that Pokémon with the Defending Pokémon.
From Ruby & Sapphire (2003) · 1 printing
Flip a coin. If heads, your opponent switches 1 of his or her Active Pokémon with 1 of his or her Benched Pokémon.
From FireRed & LeafGreen (2004) · 2 printings
Flip a coin. If heads, choose 1 of your opponent's Benched Pokémon and switch it with 1 of the Defending Pokémon. Your opponent chooses the Defending Pokémon to switch.
From HeartGold SoulSilver (2010) · 1 printing
Flip a coin. If heads, choose 1 of your opponent's Benched Pokémon, and switch it with your opponent's Active Pokémon.

Pokémon Reversal
Item
First printed in Expedition Base Set (2002)
Flip a coin. If heads, choose 1 of your opponent's Benched Pokémon, and switch it with your opponent's Active Pokémon.