Slowbro - the best prestiger in meta game

He CAN be a generalist prestiger, BUT in almost every situation there's a better choice.
For prestiging, it's not about using generalist prestiger; quite the contrary, it's about using specialist prestiger:

Water Gun + Hydro Pump/Aqua Tail for fire types and Rhydon;
Bug Bite + X-Scissor Parasect for Exeggutor;
Frost Breath + Blizzard Dewgong/Cloyster for Dragonite;
Vine Whip + Solar Beam Tangela/Ivysaur/Venusaur for Vaporeon;
Jolteon/Raichu/Electribuzz for Gyarados;
...

Each would prestige more efficiently than Slowbro.

You would only want a generalist prestiger against Snorlax. But again, the best prestiger against Snorlax, is Wigglytuff with Pound + Hyper Beam.

In most cases, vaporeon is better.

Who atk Dragonite with Slowbro!?!? Cloyster, Dewgong or Lapras are much better (no comparison lol)

I like Slowbro quite a bit. I find him undervalued in the game, especially since the nerf. But for prestiging, he is adequate at best because he doesn't have obvious matchups and his water charge move is weak on offense (Water Pulse). I use my Water Gun / Psychic Slowbros only if I have a need for a certain CP level mon and I have no other desirable options.

His best charge move is Psychic because it has STAB and is generally good against everybody but not fantastic against anybody. I find myself using Vaporeon if I need a water prestiger.

Who do you like matching Slowbro against?

I have over 390 max potions.
So i mainly use wigglytuff as common prestiger.

Max potion just feels better for pokemons that have high healt, but dont get me wrong, i dont use chansey for prestige hahahaha, way too low attack stat.