Red/Blue/Yellow only had 14 Pokemon worth having on your team outside of Mewtwo.(Broken btw)
Chansey, Exeggutor, Persian, Rhydon, Slowbro, Starmie, Tauros, Snorlax, Zapdos, Alazakam(still broken), Gengar, Golem, Jynx, Lapras.
Diamond/Pearl/Platinum gives you 48 Pokemon worth a damn.
Aerodactyl(made better), Alazakam(not so broken anymore), Azelf, Blissey(Chansey on steroids), Breloom, Bronzong(AWESOME POKEMON BTW), Celebi, Cresselia, Donphan, Dragonite(made better in D/P/Pt), Dugtrio(also made better), Dusknoir, Electrivire(Electabuzz on steroids), Empoleon(a starter that's actually useful), Infernape(another starter made useful), Flygon, Heatran, Gyarados(made better), Jolteon(made better).
I can keep going but you get the point.