This deck is based on the Lost World card which allows you to win the game if your opponent has enough Pokémon in the lost zone. To do this, we use Captivating Poke Puff as well as Palkia G Lv. X's PokePower to put the opponent's benched Pokémon in the lost zone, in addition to Gengar's attack that puts Pokémon from the opponent's hand into the lost zone. In a pinch, we have Girafarig's Get Lost puts cards from the opponent's discard into the lost zone. It's not the most consistent strategy, but with OP cards from Base Set like Computer Search and Item Finder, anything is possible! To boost consistency, we use Mew's PokeBody that allows it to use the attacks of Pokémon in the lost zone, like Lost Purge-GX. We also get to use powerful cards like Colress's Experiment because of this. Now let your opponent take an early KO and absolutely obliterate them with the power of Counter Energy! Use Porygon-Z to accelerate Energy, and Porygon2 can help draw cards.
I'm not very familiar with old cards, so if you have any suggestions on how to make the deck more streamlined, please leave a comment!
Have fun with this crazy deck!