How did you make it past the first gym in yellow?

[Absol trainer]

Mankey+ Low Kick and Nidoran M and F with Double Kick, because I always overprepared for that gym.

[Suerte17]

The first several runthroughs, I just over leveled my Pikachu. On the most recent try who knows how long back, I think I used a Butterfree. I never even thought about using Mankey. D:

[Shadow XD001]

In previous files, I'd use the Nidoran - Double Kick Combo to beat Brock, but in my most recent file I decided to make it more challenging. None of my Pikachu's moves could hit Geodude or Onix, so I had Pikachu use Tail Whip/Growl (mainly Tail Whip), then Pidgey would use Quick Attack, and I won the Badge.

[Felmarg]

I always used Mankey. This is the only point in any game where I catch a pokemon for battle that I plan on ditching right away. Normally I pick a team and stick with it.

[Forretress Fan]

There are wild Mankeys by Gary's second battle location
One lowkick equals 2 hits for Geodude and one for Onix
Pretty easy

[TicoPokemonMaster]

haha, I use to hate Geodude and Onix when I had to face them but after I would catch and train them.

When I was young I would emulate Ash's team by brock's gym I would have pikachu, butterfree, pidgeotto(lv7), and nidoran( I know it wasn't Ash's but I wanted something different, it would usually replace butterfree's place after I was bored with it.)

With butterfree I would spam Confusion and win

[GengarsRevenge]

Yeah, evolved Caterpie into Butterfree so it could learn confusion. Then it became easy.

For some reason I didn't like Nidoran, so I didn't bother training one...

[MugoUrth]

I pretty much did it the hard way. I keep leveling up my mon until I am able to beat him. But like everyone else said, if you don't want to do it the hard way, get a pokemon with a good fighting move.

[Antiyonder]

I'd pretty much just use Butterfree's Confusion and Mankey's Low Kick do the job.

Though at one point I played through Stadium to get the Surfing Pikachu (With Mew and Mewtwo as my main fighters since Pikachu would be at a low level), and used Surf attack on Brock's Pokemon.

[Noheart]

I aimed for the horn.

Oh and Butterfree.

[darkfalcon922]

nidorina>geodude and onix

[Corinton]

A level 13 Pidgey and I won the battle easily thanks to gust xD

[Mudkipz_Lover]

I just used status lowering from Pikachu, Pidgey's gust and I used Nidoran (don't remember is M or F) to waste my time to heal my Pokémon.

[Deicario]

Well, everytime I lost I'd go and face him again.
I can't remember my tram but it'd probably be easy ones to get like Pidgey (plus Pikachu
of course).
Eventually, I beat him. But I had very small amount of money left.

[sAv1Or)]

Butterfree + Confusion or Nidoran + Double Kick

[Skwog]

Either Nidoran with Double Kick or Butterfree with Confusion. I remember my first time trying to beat Brock with only Pikachu...

[hawaiian ale]

i caught a nidoran. had it evolve to a nidorina so it learned doulbe kick.

[QingLong]

A Mankey
Enough said

[The Tail]

I caught a Mankey and a Nidoran. Also Tail Whip'd the Onix 'til his defense couldn't be lowered (had a high leveled Pikachu that wistood its attacks) juust in case.

[Grannel]

Used Butterfree and spamed confusion.