I remember Bugsy being incredibly easy in GSC. The second gym leader was taken care of by Cyndaquil if you had one, but with a Pidgey/Spearow or Onix/Geodude if you chose the best starter, Tododile.
Metapod
-Harden
-String Shot
-Tackle
With the worst movepool in the game, it is obvious why Bugsy would choose this. He can easily Harden up, and wait out the game until he is KOd. At least he can do not very effective damage against your Rock type of choice, and slow it down so it goes second while its killing you. If you crammed your Pidgey, you could also Whirlwind away it's Hardens.
What it should have: Nothing can be changed, due to it's three move movepool.
Kakuna
-Harden
-String Shot
-Poison Sting
Blessed with the second worst movepool, it is more obvious why Bugsy chose to use this guy to defend his Gym. He could possibly poison you, and attempt to Harden up, and slow you down while you are whittled away. You could just Rock Throw it to death as soon as possible.
What I would change: Again, it is impossible.
Scyther
-Fury Cutter
-Leer
-Quick Attack
This Pokémon is a little more decent. It can lower your defense, and consecutively hit with Fury Cutter, and its awesome priority move, to do some comical damage while you hit it with Rocky's Rock Throw.
What I would change
-Toxic
-Rest
-Endure
-Reversal (If NPCs have egg moves)
Detect
Snore (If not)
With this set, it can Toxic Stall with reliable recovery, and Endure+Reversal can take out your Rock type of choice. Detect and Snore can also help stall, and damage even under the crippling sleep condition induced by Rest.
I remember entering the second Gym, expecting a worse hax battle, like Faulkner's infamous Sand Attack strategy. Unfortanately, I was in and out in minutes.