A PSA graded Mint 9 version of this card recently sold in auction for a whopping $250,000 USD
Other than collectors who sleeve every game they own to keep them pristine, you might want to sleeve a game where the cards aren't the best quality but you love the game and it gets played a lot, or perhaps you have picked up a game second hand and some of the cards are damaged so you want to use solid sleeves to stop people remember tell tale damage on a certain card
See the video below for an Explorer version of the deck
Mime Scyther Jynx Electrabuzz Magmar Pinsir Tauros Magikarp Gyarados Lapras Ditto Eevee Vaporeon Jolteon Flareon Porygon Omanyte Omastar Kabuto Kabutops Aerodactyl Snorlax Articuno Zapdos Moltres Dratini Dragonair Dragonite Mewtwo Mew may not be a great card, but its edgy clone is a very different matter
Legendary Creature - Elemental Fish Midnight Clock : Add
However, there are formats where this card has a massive impact against every meta deck, and in those formats, this card is occasionally found in some players' main decks