Donna

Donna is the Gym Leader of Serpentine City's Gym, known officially as the Serpentine Gym. She specializes in Poison-type Pokémon. She gives the Thorn Badge to trainers who defeat her. She is known as the queen of the poisonous kind.

In the games
Donna appears at first in Serpentine Garden. She tells the player about the beauty of this place, that she's a beginner Gym Leader and that she recieved the gym after her dad retired.

After this, she appears as the leader of Serpentine City's Gym. This gym is the first to be challenged by the player. Trainers who defeat Donna will receive the Thorn Badge, along with TM102 Fever.

Pokémon Solar Light & Lunar Dark

 * style="margin:auto"|
 * style="margin:auto"|
 * style="margin:auto"|

Rematch

 * style="margin:auto"|
 * style="margin:auto"|
 * style="margin:auto"|
 * style="margin:auto"|
 * style="margin:auto"|
 * style="margin:auto"|
 * style="margin:auto"|

Serpentine Garden
"Oh hello, I'm Donna and you are? ...oh, you are (Player's name), nice to meet you!  Isn't this garden beautiful! I come here all the time to relax after my gym battles, it's very relaxing! Oh, I'm the gym leader here, well I'm the new one, I've taken over from my father, he retired and made me the new leader, it's stressful but I think I'm finding my feet! Well, I should better get back to the gym, there could be trainers waiting for me! See you, (Player's name)!"' '

Serpentine Gym
"Oh hey (Player's name)! I'm glad you came! Well this is the gym... Well, my Gym, I guess. This used to belong to my dad, so I just started growing my roses here. I've loved Poison-type Pokémon since I was born. They can be tough, but beautiful, too. Just like every rose has its thorns! Lets do our best, okay? Choose up to three Pokémon for our battle!" "I need a bit more training..." "Even though I lost, that was a good battle! I've got a lot more to learn it seems. I'm happy to give you this. That's the official Gym Badge of Serpentine City, the Thorn Badge! Oh! Take this, too! It's a Poison-type move. It has a chance of making a foe become burned with a fever! Thanks for the battle. Good luck on your journey!"
 * Before battle
 * Being defeated
 * After being defeated

Trivia

 * Donna is seemingly related to Dawn, the female protagonist of Pokemon Diamond, Pearl and Platinum Versions; they both have similar names and both have similar outfits.