There are really only two decent bug type moves in Gen I, and confusion is not a bug type move. Its a psychic type move, which Psychic resists:
Twin Needle- Beedrill's signature move, it would be usable if A, Beedrill was not part poison type and weak to Psychic Attacks, and B, Beedrill was not slower than Sabrina's Pokemon
Pin Missile- This is learned by both Jolteon and Beedrill. Jolteon is a decent Pokemon, as it has high special attack and speed, but it does not really have the attack to fully utilize it. Beedrill, as stated above, is not to viable either
So what is one to do?
There are some things you can try to help in defeating Sabrina
1. Get yourself a Psychic Type: Psychic resists Psychic, the sole attacking type Sabrina uses. Psychic types also typically can take special hits well thanks to their good special stats. It is advisable you get a dual psychic type
2. Use powerful physical attacks: The Abra line, especially in Gen 1, are weaker on their physically defensive side. As such, it would be wise to beat down this opponent with a strong physical move, but as most physical attackers in gen 1 have poor special defense there is something you must do first
3. Status: Paralysis and Sleep can help in incapacitating the opponent's psychic type so that they may be elimated by your own psychic or a powerful physical move. Butterfree actually gets stun spore and sleep powder, so you are already in pretty good shape.
4. Level Grind: Each of Sabrina's three Pokemon, an Abra, Kadabra and Alakazaam are at a hefty level 50, and they are highly powerful for their level, especially Alakazaam. As such, it would be a good idea to level up all your Pokemon to a ludicrously high level, especially as this is a nuzlocke challenge and you dont want to lose any.
5. Be prepared for low accuracy: Sabrina's Abra and Kadabra both carry an accuracy lowering move, so it would be wise to remove them ASAP so that your Pokemon's accuracy is not lowered to ridiculously low levels, requiring you to switch it out.
Basically, the same strategy applies for beating all psychic types. Its good to have a psychic type or two or three of your own, and to inflict paralysis or sleep on the opponent's psychic, then ko them with powerful physical attacks like Earthquake or Hyperbeam.
Sabrina is an extremely tough gym leader, and will likely give you trouble, but I hope this helps you out a little, Don't limit yourself to my suggestions and best of luck to you :)
