Abra Bulbasaur Charmander Ditto Espeon Farfetch'd Grimer Haunter Ivysaur Jolteon Koffing Lapras Mankey Nidoran Oddish Pikachu Quilava (I had to cheat and look one up) Raichu Sandshrew Tentacool Umbreon Vileplume Wartortle Xatu (I had to look that one up too) Yanma (This one as well!) Zubat
Not bad for someone that only played Red/Blue over a decade ago, huh? I have no idea why I know of Espeon and Umbreon, but their names were the first ones that came up. And I also looked up Q, X, and Y and there were no Pokemon in the first set of games starting with those letters, so I don't think those should count as me failing. Huzzah!