Originally released on 3DS earlier this year (where it has been downloaded over four millions times), Pokémon Shuffle is a free to play match-3 puzzler with an energy system.
Boo and hiss all you like, it's here to stay it would seem, and anyway you don't have to download it (unless you're a die-hard Pokémon fan, I guess).
The idea is to match the heads of Pokémon in a grid in order to attack enemy Pokémon during battles. Pretty simple stuff.
There are paid-for power-ups and premium Pokéballs for anyone who doesn't mind parting with their cash.