I used Drifblim’s X and Y Pokedex entries for inspiration on the Ability and the Attack. The Ability may seem a bit overpowered, but you have to remember that Drifblim is an EX. Handing your opponent two Prizes in exchange for discarding one of their Pokemon seems fair enough for me. Its attack also may seem a bit on the strong side, but if you think about it, it really isn’t that overwhelming. Each Drifblim/Drifblim-EX you have in play counts for approximately 40 damage. You can have a maximum of 6 Drifblim/Drifblim-EX in play at once, but if you do and use Drift Off, you lose the game because you will no longer have any Pokemon in play. If you have 5 Drifblim/Drifblim-EX in play, the attack does about 200 damage, but you are left with only one Pokemon left in play (if you had six Pokemon in play originally), which your opponent can Knock Out to win the game. Also, if you used Drift Off with five Drifblim/Drifblim-EX in play, at least one of the Drifblim/Drifblim-EX would have to a non-EX Drifblim and you would have to shuffle it/them into your deck after using the resources to set them up. If you have four Drifblim/Drifblim-EX in play, the attack will do about 160 damage, which for one Energy, is really strong. Using Drift Off with four Drifblim/Drifblim-EX will leave you with a safe two Pokemon in play (if you had six Pokemon in play originally). However, it usually takes a high amount of resources to get four, or even three specific Pokemon in play, even if they are basics. In addition, Drift Off is a risky attack. You could have 5 Drifblim/Drifblim-EX in play but only hit two heads for 80 damage and have to shuffle all those Drifblim/Drifblim-EX back into your deck. I used Milotic FLF’s Energy Grace Ability for reference on the wording for the Ability and Drifblim PLB for the Weakness, Resistance, and Retreat Cost.
Hope you like my card!