Some people don't like evolutions tacked on to pokemon from previous generations, but I disagree.

ITT: Added evolutions/pre-evolutions that were good ideas.

Kingdra not only saved Seadra from total lacklusterness, but added another Dragon-type to a pokedex that, at the time, had literally only the Dragonite family to represent it. Competitive-wise, muh 100% crit ratio with the new mechanics.