Joannie "Joni" West (voiced by Brittany Wilson) is the female counterpart of Johnny Test. She made her first appearance in "Johnny Alternative" along with her best friend and female counterpart of Dukey, Dutchy. She and Dutchy teamed up with Johnny and Dukey to get rid of the counterparts of Albert and Mr. Mittens.
Joni is similar in appearance to Johnny, but with slightly brighter colors. She has blonde hair with orange highlights, also known as "flaming hair." She has blue eyes and wears pink lipstick. She wears a white shirt with a hazard sign on it, a short blue button-up jacket, green cargo trousers that have one pocket on each leg, white hi-top shoes with black laces, and a black watch. Her best friend is a genetically altered female dog named Dutchy (voiced by Maryke Hendrikse), similar to Johnny's best friend/pet Dukey.
Also, in the episode Johnny Alternative she seemed to like or have a crush on Johnny. Her first thought was disgusting, then later on he ended saving her from being turned into a kitten, she was touched and they almost ended up kissing but Johnny went back to his world.
- Unlike Johnny, she isn't a good shot.
- Joni has a tendency to place one of her hands in her pocket.
- Both she and Johnny can climb trees well and often take things from their siblings.
- Unlike Johnny and Dukey, she and Dutchy don't know how to use the weapons they use.
- Johnny saved her from turning into a cat by jumping in front of the blast from a cat ray fired by Madame Mittens.
- She gives her brothers coupons like Johnny for free experiment tests.
- She and Johnny have similar hand writing as shown when her brother Mark holds up a free test coupon.
- She and Dutchy may have not realized that Johnny and Dukey are their male counterparts.
- Her hairstyle resembles Adyson Sweetwater's hairstyle from Phineas and Ferb.
- It is unknown if she will make another appearance.
- Joni greets her brothers by saying ''Hey Brainy Bro's''
- It's possible she might have a superhero personality like Johnny does.
- It is unknown what superhero personality's name would be, though a possible name may be "Joni X".