As of yesterday, November 21, 2016, many Pokémon had their CP either raised or lowered. Which ones had their CP changed?
From this site:
These Pokémon had their CP increased:
Abra, Aerodactyl, Alakazam, Beedrill, Butterfree, Chansey, Charizard, Cloyster, Diglett, Dodrio, Doduo, Dragonite, Dugtrio, Electabuzz, Electrode, Exeggcute, Fearow, Flareon, Gastly, Gengar, Geodude, Goldeen, Golem, Graveler, Gyarados, Haunter, Hitmonchan, Hitmonlee, Horsea, Jolteon, Jynx, Kabuto, Kabutops, Kadabra, Kangaskhan, Kingler, Krabby, Machamp, Machoke, Machop, Magnemite, Magneton, Mankey, Marowak, Moltres, Mr. Mime, Muk, Omanyte, Omastar, Onix, Pinsir, Primeape, Raticate, Rattata, Rhydon, Rhyhorn, Sandshrew, Sandslash, Scyther, Seadra, Shellder, Snorlax, Starmie, Tangela, Tauros, Tentacool, Tentacruel, Vaporeon, Venomoth, Voltorb, Zapdos
These Pokémon had their CP decreased:
Arbok, Arcanine, Articuno, Bellsprout, Blastoise, Bulbasaur, Caterpie, Charmander, Charmeleon, Clefable, Clefairy, Cubone, Dewgong, Dragonair, Dratini, Drowzee, Eevee, Ekans, Exeggutor, Farfetch’d, Gloom, Golbat, Golduck, Grimer, Growlithe, Hypno, Ivysaur, Jigglypuff, Kakuna, Koffing, Lickitung, Magikarp, Magmar, Meowth, Metapod, Nidoking, Nidoqueen, Nidoran, Nidorina, Nidorino, Ninetales, Oddish, Paras, Parasect, Persian, Pidgeot, Pidgeotto, Pidgey, Pikachu, Poliwag, Poliwhirl, Poliwrath, Ponyta, Porygon, Psyduck, Raichu, Seaking, Seel, Slowbro, Slowpoke, Spearow, Squirtle, Staryu, Venonat, Venusaur, Victreebel, Vileplume, Vulpix, Wartortle, Weedle, Weepinbell, Weezing, Wigglytuff, Zubat
In addition, Lapras' CP was unaffected.
For a reading on exactly how much the CP was changed by, see these images.