Which does it best? Water/Fighting

@Hades0918 Red's starter in the manga is a Poliwhirl(forget if he got it as a Poliwag but it's introduced as a Poliwhirl) that eventually evolves into Poliwrath. He gets a starter(Bulbasaur) from Professor Oak and catches a Pikachu in Pewter City(not Viridian Forest like most players that are lucky enough to get the rare encounter). He then catches a Snorlax, an Eevee that can change into any of its three Kanto forms(OP no?), Nidoqueen, Nidoking, Victreebel, Krabby(that he trades to Misty for Gyarados), Aerodactyl (via Old Amber), and other Pokémon. Even gets Mewtwo via Master Ball but gives it to Blaine. TLDR: Red's Manga team is different from the one in G/S/C or HG/SS. Let's GO Pikachu/Eevee has several Manga Pokémon, including his Kanto starter. It just doesn't have Poliwrath. If it did, I'd like the game a bit more.

As for which Pokémon does Water/Fighting the best is subjective. I personally like Poliwrath, although I haven't used it since Gen 1 was not kind to it and Poliwag is just so weak early on. Even Poliwhirl leaves a bit to be desired. Yet if there is one knock on Poliwrath is that it loses 20 Speed from Poliwhirl. Even Politoed loses 20 Speed but Poliwrath has 510 base stats, which isn't bad.

No Red had that Eevee. Apparently Team Rocket experimented with it and hence it's a rare Eevee as a result. Three Kanto Gym Leaders are Team Rocket Admins: Lt.Surge(who is Electrocuted by equipment he was wearing after being damaged by Red's Saur(aka Bulbasaur nickname), Koga(Blue's Charmeleon slices his Arbok in half. Survives that btw) and Sabrina(forget what happens to her but she's a tough cookie. Red acquires their Gym Badges after each fight). Makes Team Galactic seem like small fries when you got Gym Leaders in your organization. Giovanni gives him Old Amber but no stones if I recall correctly.