The Kanto Expansion Pak is a ROM hack of Pokémon Red that expands the chromatic generation with scrapped Pokémon, regional variants, and cross-gen evolutions.

Moving through the generations might be a good way forward. While there are plenty of others included in Genetic Apex, its primarily a Kanto expansion hence the Mew reward for completing that ...

Completing the Kanto Pokedex in Pokemon TCG Pocket rewards players with a secret Mew card. To quickly complete the card collection, open daily packs, earn Shop Tokens, & use Pack Hour Glasses.