A New addition to the world of Pokemon is that of Alolan Forms. These are certain Pokemon - all of which from the First Generation - that have developed differently to how they originally have been outside of The Alola Region in order to better survive, which often sees these Pokemon taking on new appearances and developing new types, Stats and abilities.
When you transfer one of these given Pokemon from a previous game and breed them, you will get that Pokemon's Alola Form. However, if you attach an Everstone to said Non-Seventh Generation Pokemon and breed them, you will get their regular form found everywhere outside of Alola. You cannot evolve into standard Raichu, Exeggutor or Marowak in this game; you must transfer them in said Forms to obtain them.
18 First Generation Pokemon That Received An Alolan Form:
Rattata
Typing: Dark / Normal
Abilities: Gluttony / Hustle / Thick Fat
Base Stats: 30/56/35/25/35/72
Raticate
Typing: Dark / Normal
Abilities: Gluttony / Hustle / Thick Fat
Base Stats: 75/71/70/40/80/77
Raichu
Typing: Electric / Psychic
Abilities: Surge Surfer
Base Stats: 60/85/50/95/85/110
Sandshrew
Typing: Ice Steel
Abilities: Snow Cloak / Slush Rush
Base Stats: 50/75/90/10/35/40
Sandslash
Typing: Ice / Steel
Abilities: Snow Cloak / Slush Rush
Base Stats: 75/100/120/25/65/65
Vulpix
Typing: Ice
Abilities: Snow Cloak / Snow Warning
Base Stats: 38/41/40/50/65/65
Ninetales
Typing: Ice / Fairy
Abilities: Snow Cloak / Snow Warning
Base Stats: 73/67/75/81/100/109
Diglett
Typing: Ground / Steel
Abilities: Sand Veil / Tangling Hair / Sand Force
Base Stats: 10/55/30/35/45/90
Dugtrio
Typing: Ground / Steel
Abilities: Sand Veil / Tangling Hair / Sand Force
Base Stats: 35/100/60/50/70/110
Meowth
Typing: Dark
Abilities: Pickup / Technician / Rattled
Base Stats: 40/35/35/50/40/90
Persian
Typing: Dark
Abilities: Fur Coat / Technician / Rattled
Base Stats: 65/60/60/75/65/115
Geodude
Typing: Rock / Electric
Abilities: Magnet Pull / Sturdy / Galvanize
Base Stats: 40/80/100/30/30/20
Graveler
Typing: Rock / Electric
Abilities: Magnet Pull / Sturdy / Galvanize
Base Stats: 55/95/115/45/45/35
Golem
Typing: Rock / Electric
Abilities: Magnet Pull / Sturdy / Galvanize
Base Stats: 80/120/130/55/65/45
Grimer
Typing: Poison / Dark
Abilities: Poison Touch / Gluttony / Power of Alchemy
Base Stats: 80/80/50/40/50/25
Muk
Typing: Poison / Dark
Abilities: Poison Touch / Gluttony / Power of Alchemy
Base Stats: 105/105/75/65/100/50
Exeggutor
Typing: Grass / Dragon
Abilities: Frisk / Harvest
Base Stats: 95/105/85/125/75/45
Marowak
Typing: Fire / Ghost
Abilities: Cursed Body / Lightningrod / Rock Head
Base Stats: 60/80/110/50/80/45