It's a 2/3 creature for 5 mana that just untaps and allows your dorks to have flash
if you banish Mewtwo EX with Sabrina, it can still come back and get two Energy per round with Gardevoir: if you want to KO it, you need an equally strong, equally Energy-reliant attacker like Charizard EX, who Mewtwo can deal with pretty handily as a Basic Pokemon
This event is extremely recognizable, and it makes this Energy card one of the coolest from a design standpoint, and this Grass one is just extra perfect for including Celebi

Agrus Kos, Spirit of Justice Ajani Vengeant Ajani, Nacatl Avenger Akiri, Line-Slinger Alibou, Ancient Witness Alibou, Ancient Witness Anya, Merciless Angel Arcee, Acrobatic Coupe Arcee, Sharpshooter Aurelia's Fury Aurelia, Exemplar of Justice Aurelia, the Warleader Aurelia, the Warleader Bruse Tarl, Boorish Herder Catharsis Chance for Glory Cloud, Planet's Champion Comet, Stellar Pup Eivor, Battle-Ready Excava, the Risen Past Explosive Getaway Feather, Radiant Arbiter Fight to the Death Gisela, Blade of Goldnight Hofri Ghostforge Huatli, Dinosaur Knight Huatli, Warrior Poet Iroas, God of Victory Kalemne, Disciple of Iroas Kassandra, Eagle Bearer Legion's Initiative Lightning, Army of One Lorehold, the Historian Nahiri, Forged in Fury Nahiri, Heir of the Ancients Nahiri, the Harbinger Nahiri, the Unforgiving Nelly Borca, Impulsive Accuser Neyali, Suns' Vanguard Osgir, the Reconstructor Otharri, Suns' Glory Outlaws' Merriment Phlage, Titan of Fire's Fury Photon, Living Light Quintorius Kand Quintorius, History Chaser Sami, Wildcat Captain Velomachus Lorehold Warleader's Call Waves of Aggression Winota, Joiner of Forces Wyleth, Soul of Steel

If heads, your opponent's Active Pokemon is now Confused
Prices are updated based upon Magic Core Set 2021 listings that sold on eBay and other marketplaces