To get the Pokemon TCG Pocket Mew card, as mentioned above, you need to complete the Kanto Pokedex, which means getting at least one of every of the original 150 Pokemon in the game. Once you do so, an option will come up in your "missions" tab to complete the quest and reward you with the Mew card itself, like any other mission reward.

Despite the non-answer from the devs and Pokémon Company, you can find people who have dug into the code and looked at how Pokémon Trading Card Game Pocket actually works and according to their findings, the pack you pick doesn’t matter. So why won’t The Pokémon Company say that?

The simplest way to pull a Misty card in Pokemon TCG Pocket is by opening the Pikachu packs in the Genetic Apex set. There are two versions of Misty: a common one, which is a Two-Diamond Rarity, and then a card with full card artwork, which is a Two-Star Rarity.