I get some of your choices.

- Blastoise because it can shoot water in order to extinguish fire, which is Marshall's whole thing since he is a firefighter;

- Blaziken because it is a Fire/Fighting type, which I guess is a pun on the word ''firefighter'';

- Flareon because of its fire biology;

- Hitmonlee COULD work, since again, it's Fighting type, bringing up the fire ''fighter'' pun once again;

- Golduck since its water attacks can put out fire, same as Blastoise;

- If I had to choose between Zacian and Sirfetch'd, I'd go with Sirfetch'd simply because of the fighting pun once again.

Ok and is blastiose reference to Marshalls water cannons and goldduck reference to Marshalls duck friend and hitmonlee reference to Marshalls pup fu skills and Blaziken and Flareon is reference Marshall might pups power and his change up and zacian and sirfetch is reference to pups and Ryder went to barkbird for 3 subseries