Much like all Pokemon Games prior to this one, a player will still be able to receive a number of Gift Pokemon from other characters during their journey through The Alola Region. In total, a player can obtain up to fourteen Gift Pokemon during the game, one of which happens to be your Starter Pokemon.
Gift Pokemon
Starter Pokemon - Route 1: As the game first begins, your trainer will go exploring. Before you reach the first Wild Grass on Route 1, you will be attacked by a Yungoos. After getting ambushed, the three Alola Region Starter Pokemon will appear and scare off the Yungoos. Professor Kukui will then appear and will allow you to have one of them. Each Pokemon will be at Level 5, and they include Rowlet, Litten and Popplio.
Eevee - Paniola Ranch: The first time you ever visit the Pokemon Nursery in Paniola Ranch, you will be given an Egg by the owner. This Egg will later hatch into a Level 1 Eevee, which you can later evolve into one of its eight Evolutions.
Porygon - Aether House: After defeating the Elite Four for the first time, there will be an Aether Employee at the Aether House that will give you a Level 30 Porygon as a thank you gift for helping save The Alola Region.
Aerodactyl - Seafolk Village: Once you arrive in Seafolk Village, there is a young trainer in Huntail Boat that will give you an Aerodactyl for nothing at all. It will be at Level 40.
Pikachu - Heahea City: After you have defeated all the high scores in each of the four different Mantine Surf Courses on each island in The Alola Region, you can go to the man in the Surfing Association Office in Heahea City to receive a free Pikachu at Level 40. THis Pikachu is special in the fact that it knows the move Surf.
Poipole - Ultra Megalopolis: After defeating Ultra Necrozma at the top of Megalo Tower, the Ultra Recon Squad will gift you with Poipole for helping them defeating Necrozma. This is the first Ultra Beast you can obtain, and it comes at Level 40.
Type: Null - Ancient Poni Path: After defeating the Pokemon League and visiting the Ancient Poni Path once again, Wicke will appear and give you a Type: Null that Gladion would like you to have. It will be at Level 60, and Wicke will give you all of its Memory Drives at this time as well.
Zygarde - Route 16: After defeating the Elite Four and capturing Zygarde in Resolution Cave, you can visit Dexio and Sina in the lab on Route 16. If you defeat Dexio in a battle, you will be awarded a Zygarde at Level 63, the same that can help you build a Zygarde with the ability Power Construct (and thus obtain Zygarde 100% Form.
Totem Sized Pokemon (7 Pokemon) - Heahea Beach: As you collect the Totem Stickers placed across the four islands of The Alola Region, you can return to Heahea Beach to obtain certain Totem Sized Pokemon from Samson Oak after obtaining specific amount of stickers:
20 Totem Stickers - Gumshoos
40 Totem Stickers - Marowak
50 Totem Stickers - Lurantis
70 Totem Stickers - Vikavolt
80 Totem Stickers - Mimikyu
100 Totem Stickers - Ribombee