In Crackle!! Practice Battle, Henry and Casey sought to impress Leon with their battling skills by driving off a wild Obstagoon in the hopes of him endorsing them for the Gym Challenge. True to their hopes, Leon soon contacted Rose regarding the endorsements he was planning to give to the two Trainers he had just met.
In Chomp!! Defeat Drednaw, Henry and Casey's endorsement became widespread knowledge amongst the Gym Leaders, who where surprised to hear that Leon had decided to endorse two Trainers at once.
In Blazing!! Bede's Feelings, Bede mentioned that he had been endorsed by Chairman Rose.
In PASS21, Hop revealed that Leon had offered to endorse him as well, but he had turned his offer down, not wanting to make Leon look bad by possibly performing badly after being endorsed by him.