Pokémon attacks which deal no damage
They might be just weak cards designed as a filler for an expansion, but most of the time those cards can further evolve into much stronger Pokémon.

Speaking about Cosmog and Cosmoem, those cards mimic their console game counterparts where they are small and mostly useless. But Cosmoem is able to evolve into either Solgaleo or Lunala which are both strong lengendary Pokémon. In TCG, you can evolve in either of them without any limitation.

Here are all the cards Cosmoem can evolve into as of April 2019, you can see that they are nowhere near being useless: