Theres a long line of articles stretching back years discussing the times when its appropriate to use Surgical Extraction, Slaughter Games, Memoricide, and the like, and when (more frequently) one should avoid sideboarding those types of cards when alternatives are more valuable
While it may not outright kill opposing creatures, it deals damage to smaller ones and taps the rest, ensuring your team can attack without opposition
You can just imagine that Riolu used this cards move, Reckless Charge, to cause this amount of destruction.
In Pokmon Trading Card Game Pocket, opening either the Genetic Apex Mewtwo, Pikachu, or Charizard booster packs freely will likely set you back on your way to building a full collection and a competitive deck as each one offers different cards and different early-game rewards