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Johto had 251 new Pokemon.
Due to the splitting the special stat into special attack/defense and completely changing up the sprites to the modern incarnations of the designs, even if a Pokemon shared its name with one from the prior generation they have nothing in common beyond that.
No Pokemon game has ever had more new Pokemon than Johto and it was nice enough to let Kanto feast on its scraps in future remakes.
Gen 3+? You will never compare.
Gen 1? Thanks for beta testing.