The cutest character from Kanto
Some readers believe that despite my claims that all Pokémon have personality, there are still some that are too bland to receive their own analysis. However, the Pokémon they are thinking of do have personality and have undergone some character development — even if they are a small, blue Pokémon that can’t maneuver itself on land with only a handful of appearances in the anime. Misty's Horsea is actually a character rich in personality and if he were not unable to walk, everyone would know it.
In Horsea’s debut he was shown to care deeply for a consensual society (consensus means "harmony in society"). Horsea knew how the building of the hotel would affect the Tentacool, but disagreed with them fighting it. Horsea had some confrontation with the Tentacool, presumably, and tried to steer them away from violence, not in the spirit of giving up but for reason of keeping the peace. However, Horsea’s words fell on deaf ears and he was attacked, leading him up to the point where he, battered and bruised, met Misty and her friends. Still believing he could make a difference, Horsea sought help from the three.
Horsea’s passion to make things right shows that he constantly feels responsible for anything he could possibly fix or sort out. This can be explained by thinking about Horsea's childhood: if, as a child, swimming in his school, Horsea had a lot of responsibility within his family, he would likely still feel he has the same responsibility now. This concept is similar to John Bowlby’s theory of attachment, where the child builds their own internal working model of how their relationships should be in the future, comparable to a child having responsibility in its family and later believing it will have to same purpose in contemporary society. It would also make sense to propose that Horsea grew up in an environment without conflict and by the same theory, Horsea believes all of culture and society should be without conflict, a trait that disappeared after his experiences with Team Rocket, teaching him that people are not always nice and crime and deviance will never end — in fact they are functional for society. Horsea had development as well, moving from shouting at the giant Tentacruel in his debut, convincing it with words alone, to finally battling Team Rocket in The Misty Mermaid.
Another thing notable about Horsea, and perhaps another thing that indicates he had a lot of responsibility in his family, is how good and friendly he is with children. He was first shown in this light when he, along with his trainer, consoled Mikey about his problem with his brothers and Eevee, once again getting involved with a conflict. Again he showed compatibility with children when all of the gang’s Pokémon were sent out to play on Children's Day, where Horsea used his Bubble attack to amuse the children, without command and without an indication, whereas all the others seemed to have the children run up and pet them and climb on them. All of this could indicate that Horsea has a possible desire for parenthood.
Horsea was also shown to be one of the smarter Pokémon in the gang’s family, having devised a way to be able to communicate with humans, simple as it may have been (Horsea drew a picture of both Tentacool and Tentacruel in the water with his ink, which Ash and the others were able to decipher). Then when all the Pokémon at the evolution stone festival were stolen by Team Rocket and driven away in a truck, Horsea independently figured out if he squirted a trail of ink behind the truck from his cage, the people at the festival would be able to track them down. Once again, he took it upon himself to fix the situation.
Horsea, although not having a lot of notable development in the series, provided important development to the writing of the series itself. Horsea showed the writers they could not pull off a convincing character when the Pokémon could not maneuver on land, so he appeared seldom. However if Horsea could have moved himself on land, he would have had the makings of a great and memorable character, that we all would recognize as a character, blooming with personality.