Dawn took quite some time to become the Pokemon trainer and contest coordinator that she dreamed of being.
At first, she was as green as grass. Dawn had very little idea what it would take to become a master of contests and a trainer that her Pokemon could trust. It was shown throughout the anime as her partners disobeyed.
Eventually, she proved her worth as a trainer. Perhaps the anime needed to give her a little something more. There are some Pokemon that would have fit right in with her team and her aspirations.
Note: This article is subjective and reflects the opinion of the writer.
Top 5 Pokemon Dawn should've trained in the anime
#5 - Milotic
Pokemon contests are all about coordination, beauty, and skill as a trainer and as a Pokemon. There aren't many creatures more beautiful than Milotic. If Dawn was able to get Feebas and evolve it, her contest days would have been much easier. Milotic is not just a pretty face, it is also one of the most powerful Water-type Pokemon around.
#4 - Primarina
While Primarina entered the Pokedex after Dawn's journey started, it would have been a wonderful contest partner. It is elegant and strong. Primarina is a Pokemon known for dancing and showing off. If Dawn were able to train one to participate in contests with her, as she grew more experienced, it would be pretty hard to be the pair.
#3 - Typhlosion
Dawn had an Egg that hatched into a Cyndaquil. Cyndaquil remained in first form for a very long time. Eventually, it evolved into Quilava. Unfortunately, it never evolved further than that. It would have been great to see Dawn continuing training Quilava to be able to eventually train it as a Typhlosion. Pokemon has a problem with trainers not taking creatures to their limits.
#2 - Empoleon
The same issue happened with Piplup. Piplup was the starter Pokemon that Dawn chose. It is often seen bickering with its trainer and not competing to the best of its abilities. That did change over time as Piplup and Dawn became closer and more trustworthy of each other. It forever remained a Piplup. The possibilities of her evolving it to train an Empoleon are endless.
#1 - Mesprit
Dawn was said to have a unique ability to connect with the emotions of Pokemon. Mesprit is said to have taught humans the ability to feel sorrow, pain, and joy. It is known as the Emotion Pokemon. In the anime, Dawn helped free it and it helped stop Cyrus' evil plan. The fact that it appeared before Dawn, and both of their connections with emotions, would have given her a great Legendary to train.