So Slowbro is a great choice if it is actually the original Silver.
With a great Satk compared to Gyarados and Quagsire, it can abuse a necessary move ingame, Surf. It also got access to Psychic which is awesome against Koga and Bruno the Elite Four. It also has a myriad of weird and epic moves, such as Zap Cannon, Blizzard, Shadow Ball and Fire Blast!
And what it lacks in Speed, it makes up for in bulk, with excellent 110 Defense and 95 HP, it can take hits from the likes of Golem and Machamp easily. Here is a moveset:
-Water Gun ->Surf (replace Water Gun when you get Surf)
-Confusion->Psychic (replace Confusion when you get Psychic)
-Zap Cannon/ Shadow Ball /Fire Blast
And not to mention its resistances! While Electric and Grass can dent it quite badly, it is pretty much killing anything else. Bugs had no really good move until Gen 3(Twineddle is VERY intimidating though) and with only 4 Ghosts in the entire game, you shouldn’t have to worry. And while the random Bites of Ratata might be annoying, Darks was both uncommon and weak in Gen 2 compared to how they are now.
But it is not all Sunshine for the Bro though. It can be found very early, in the Slowpoke Well, but it also stay Slowpoke for quite a while, until Lv 37 and as I said, its speed is rock bottom, and with no access to Trick Room, it can prove difficult to use.
That is the pure awesomeness of the Bro, fear him, love him, train him!