Recommendations: 
I would say Fighting Types to just go all out attack on her Normal Type Pokemon.
One example would be Machop. You can find a person who has one on the 5th floor of
Goldenrod City's Department Store. The person will trade you it for a Drowzee.

 Goldenrod Gym: 
Hey, welcome to the Goldenrod Gym. To reach Whitney, you must travel on the raised floor,
navigating through the maze and encountering Trainers along the way.
 Trainer Teams: 
 Beauty Akemi
 Sentret Lv.9
 Sentret Lv.13
 Sentret Lv.16
 Beauty Naoko
 Meowth Lv.16
 Meowth Lv.16
 Lass Mika
 Snubull Lv.17
 Lass Asuka
 Jigglypuff Lv.15
 Jigglypuff Lv.15
 Jigglypuff Lv.15
At the end of this maze is Whitney, the trainer of Normal Type Pokemon.


"Hi! I'm Whitney! Everyone was into Pokmon, so I got into it too! Pokmon are super-cute!
You want to battle I'm warning you--I'm good!"

 Whitney, The Dynamic Pretty Girl!: 

 Clefairy: 
 Level: 
 17
 Type: 
 Normal
 Ability: 
Cute Charm ~ Contact with this Pokemon may cause infatuation
 Moves: 
Double Slap
Mimic
Encore
Metronome
 Review: 
 if you want to be on the safe side, use a Rock Type Pokemon on Clefairy. It only uses
Normal Type Moves (Not counting Metronome) Double Slap will hit from 2-5 times in a row.
Mimic will copy he opponents last move and use it. So if I am a Rock|Ground Type Pokemon
and I use Earthquake on Clefairy and it survives, it could use Mimic on me, so I'm
screwed. Encore will make the opponent Pokemon use the same move it used last time the
only move it can use, for a period of time. Metronome is an odd move. It selects one
random move out of  the opponent. Also, try to use SPecial Moves on Clefairy, due to its
ability.

 Miltank: 
 Level: 
 19
 Type: 
 Normal
 Item: 
 Lum Berry
 Ability: 
Scrappy ~ Enables moves to hit Ghost Types
 Moves: 
Rollout
Attract
Stomp
Milk Drink
 Review: 
 The Cow can be annoying if it uses certain moves. It can use Stomp to give decent damage
to the opponent.
Roll Out will hit the opponent for 5 turns and it gets stronger every time it is used.
Attract will infatuate  the opponent, and don't expect to recover from it quickly. You
won't be able to attack while you are infatuated. This will let Miltank recover by using
Milk Drink or try to KO your Pokemon.
"Sob... ...Waaaaaaah! You're mean! You shouldn't be so serious! You...you child, you!
Waaaaah! Waaaaah! Snivel, hic...You meanie!"
"...Sniff... What What do you want A badge Oh, right. I forgot. Here's the Plain Badge."

 Fun Facts: 
~Whitney has one more Pokemon on her team in the anime. It is a Nidorina.
~The maze in the gym resembles a Clefairy
~The Dynamic Pretty Girl is Whitney's Japanese Leader Title
 Results: 
~You get to use TM Strength outside of battle
~You get TM 45 Attract
 Special Thanks: 
~Bulbapedia
~You for reading