Friendship (also known as Happiness) is an aspect in the Pokémon games. It is literally the bond between Trainer and Pokémon. Friendship can be gained by winning battles, using certain items and healing the Pokémon. The higher the friendship, the more the Pokémon likes the Trainer. All Pokémon can reach high friendship (although strong Pokémon and Legendary Pokémon, and, for unknown reasons, Buneary, are hard to befriend). Also, some say that if a high-level Pokémon has the highest friendship level with a trainer and it was another's Pokémon, it will listen to you. This is not the case if you don't have the respective number of badges; but even if the Pokémon is friendly towards you, they still will not listen to you.

In the Games[]

In HeartGold and SoulSilver, the aspect of friendship can be viewed by interacting with the Pokémon in front of the party. When friendship is high, Pokémon can show signs of affection towards their respective trainers. Some of these signs can be strong. Friendship can determine the power of Return or Frustration. If the Pokémon's friendship is high, it likes its Trainer and the power of Return increases while the power of Frustration decreases. If the Pokémon's friendship is low, it dislikes its Trainer and the power Frustration increases, while the power of Return decreases. Capturing a Pokémon with a Luxury Ball, attaching a Soothe Bell to the Pokémon, or giving it Berries that augment Stats are also ways to increase friendship with Pokémon. However, allowing the Pokémon to faint in battle and letting it get injured a lot will decrease its Friendship to the trainer, making the Return attack weaker, but making Frustration stronger.

Friendship can also help certain Pokémon evolve, such as Togepi into Togetic and Golbat into Crobat. Many Baby Pokémon evolve into their base Pokémon though Friendship. Additionally, in Diamond, Pearl, and Pokémon Platinum, one can check their Pokémon's friendship level with a Pokétch app.

Friendship can also help certain Pokémon with their special moves. In Pokémon: Let's Go, Pikachu! and Pokémon: Let's Go, Eevee!, both Partner Pikachu and Eevee require a high level of Friendship in order to activate their Special Moves: Pika Papow and Veevee Volley.

Friendship Evolution Pokémon[]

List of Pokémon Evolves by Friendship
Name	Conditions	Evolve to
Golbat	None	Crobat
Alolan Meowth		Alolan Persian
Chansey		Blissey
Pichu		Pikachu
Cleffa		Clefairy
Igglybuff		Jigglypuff
Togepi		Togetic
Azurill		Marill
Buneary		Lopunny
Munchlax		Snorlax
Woobat		Swoobat
Swadloon		Leavanny
Type: Null		Silvally
Eevee	at Day	Espeon
Budew		Roselia
Riolu		Lucario
Eevee	at Night	Umbreon
Chingling		Chimecho

In the Anime[]

In the anime, the bond between Trainers and their Pokémon has been a main theme since the first episode, in which Ash had trouble trying to form a friendship with his newly obtained Pikachu. After risking his own safety to protect his First partner Pokémon from a flock of angry Spearow, Ash earned Pikachu's trust, and the two have been inseparable ever since.

It's said that Pokémon who have friendly relations with their Trainers perform better in battles. Ash believes that friendship with Pokémon will make him stronger and almost invincible, and he treats all his Pokémon friends with a special care and respect, bordering on love.

However, some Trainers, such as Paul and Cross, have been shown to focus on raw strength alone, disregarding their Pokémon's feelings and well being over the course of the series.

In the case of Greninja, his bond with Ash was so strong that he is able to use the power of Bond Phenomenon to activate Ash-Greninja mode, which may be able to surpass even Mega Evolution.