Search! Strongest Friends (Japanese: さがせ！さいきょうのなかま) is the fourth The Pokémon Tretta series set, and the twelfth overall. It features 48 Tretta.
Search! Strongest Friends once again features the Combo mechanic, last used on Tretta from the Witness Genesect! set. Tretta that can perform a Combo from this set have a icon; however, they cannot perform a Combo with Tretta from Black Kyurem & White Kyurem and promotional Rookie Tretta made available around that time, despite featuring the same icon. Therefore, Tretta can only perform a Combo providing they have like Combo icons and are from the same series.
Standard Tretta in Search! Strongest Friends are colored green. The Legend-class Tretta features the Temporal Pokémon Dialga, and the Secret Tretta features the Forbidden Pokémon Spiritomb. The set also includes three more Pokémon that can Mega Evolve: Charizard (into Mega Charizard X), Gengar, and Tyranitar. Tretta featuring Gengar in this set are Shiny, and their ability to Mega Evolve are tied in with the White Mega Gengar Campaign and the distribution of a special Gengar for Pokémon X and Y.
The comparatively large selection of Ghosttypes ties in with the Halloween-inspired Thriller Hills and its autumn themed Search Mode locations. For the first time, Waterfront is not included as a location, replaced with another new location: Park. Search Mode is again slightly expanded, with the potential for two Pokémon to occupy one location. After zooming in to a location, the player can choose one of the two shaking areas if two Pokémon are present, and reveal one of them before going to the next location.
Roulette Chance (Japanese: ルーレットチャンス) was also added to Catch Mode in this set. If a higher grade Poké Ball is adjacent to the one selected on the roulette, Roulette Chance may activate and prompt the player to repeatedly press the Poké Ball button on the console in order to nudge the roulette and earn a better Poké Ball.