Yeah, you can't.When Golbat gains enough happiness, it will start to evolve, but the evolution will suddenly stop like you've pressed B, even if you haven't.
You have to get the national dex first.
...but on topic, I think that Snorlax, or even Magneton are other good choices.
a butterfree with silverwind would do a good job. but thatd take ages to lget if youre only in celadon..
yeh, dugtrio or snorlax would be pretty good. although anything pretty strong with bite might work a treat. or even a haunter, i guess thatd be a good one to use as long as it was at a high enough level.
I depends on how you choose to raise your pokemon. If you go for a one-pokemon powerhouse(like me with my starter) then use your powerhouse and totaly demolish that alakazam with barely a scratch. If you CAN be bothered to raise another pokemon, then go for haunter/gengar(if possible) considering their ghosts it'll be no sweat.