A list of Pokémon who debuted in Pokémon Diamond and Pearl.
Introducing 107 new Pokémon, this gen is the fifth-smallest, behind Generations II, VII, VIII, and VI. However, due to it introducing a whopping 29 Pokémon related to older Pokémon, it stands, at 78 Pokémon, as the third-smallest generation going by its own Pokémon (and, in fact, is just half the size of Generation V).
Generation IV's general character design appears to be a culmination of the previous generations, as this is the generation that revisited older Pokémon and gave them evolutions to make them more viable or baby forms to make them more marketable. However, that isn't to say that the new Pokémon were overshadowed, as monsters such as Lucario and Garchomp cemented themselves in the minds of most fans.
If Ultra Beasts are not counted as Olympus Mons, and if one classifies a certain Pokémon related to one of the Mythicals as one, this generation is also tied with Generation VII for the one that introduced the largest number of Olympus Mons, with four Mythical Pokémon, the two expected trios, and three miscellaneous Legendary Pokémon (including one unrelated to anything else), for a total of fourteen.
For other generations, go here.
