Figuring out which Pokémon TCG Pocket deck to try and collect can be tricky. Luckily, the game includes several rental decks to help with this process. Rental decks are fully constructed decks that players can unlock to get a feel for a certain Pokémon and its strategies. Collecting the highlighted Pokémon from each rental deck will unlock it for temporary use, which is nice because new players can try the decks out without owning every card. After 10 uses, players will need to unlock every card in a rental deck to unlock it permanently.

https://screenrant.com/pokemon-tcg-pocket-how-get-best-rental-decks/