Ok so this is in black 2. I have an azumarill and its my hm slave for strength, waterfall, surf, and dive. Is there a better comp. Pokemon that can learn these hms? I only throw it out to revive one of my other, more battle competent, mons, so it has to be tanky.
No, Azumarill is not the best HM slave since you can catch Eevee early in the game, after the third gym in Castelia Sewers, and evolve it into Vaporeon. Vaporeon is much bulkier than Azumarill as it has more HP, and a better special defense. On the other hand, Psyduck also can be caught in the same place as Azurill, however it's not as bulky. Vaporeon is also bulkier than Golduck as it's defenses and HP stats are superior. A water stone for Eevee can be found in Route 19, but it will require surf, which your Azumarill already knows.
Golduck's Pokedex- https://pokemondb.net/pokedex/golduck
Azumarill's Pokedex- https://pokemondb.net/pokedex/azumarill
Eevee's Pokedex- https://pokemondb.net/pokedex/eevee
Vaporeon's Pokedex- https://pokemondb.net/pokedex/vaporeon
sumwun's link- https://pokemondb.net/black-white-2/hms
And experience from using a HM slave in BW2