Synthesis

In Pokémon ChampionsGen II

Game

Pokémon Champions

GrassStatus

Heals the user by a weather-dependent amount.

Power: –
Accuracy: —
PP: 5
Hits: The user

Changes over time

How Synthesis changed from game to game, newest first.

Gen IX
… maximum HP if the weather is ~~dropped: Hail,~~ Heavy Rain, Rain, added: Sandstorm, or ~~dropped: Sandstorm,~~ added: Snow, all rounded half down.
Gen VIII
… or no weather conditions are in ~~dropped: effect,~~ added: effect or if the user is holding Utility Umbrella, 2/3 of its maximum HP if …
Gen VI
The user restores 1/2 of its maximum HP if added: Strong Winds or no weather conditions are in effect, 2/3 of its maximum HP if the weather is added: Intense Sun or Sun, and 1/4 of its maximum HP if the weather is Hail, added: Heavy Rain, Rain, or Sandstorm, all rounded half down.
Gen V
… Hail, Rain, or Sandstorm, all rounded added: half down.
Gen III
… no weather conditions are in effect, ~~dropped: all~~ added: 2/3 of its added: maximum HP if the weather is Sun, and 1/4 of its maximum HP if the weather is ~~dropped: Rain~~ added: Hail, Rain, or Sandstorm, all rounded down.

Numbers: PokéAPI’s changelog. Descriptions: Pokémon Showdown’s for each generation, PokéAPI’s notes where Showdown’s don’t differ. Champions: Pokémon Showdown.

See it in the games

No clip of Synthesis here yet. Find Synthesis on YouTube →

How it works in Champions

The user restores 1/2 of its maximum HP if Strong Winds or no conditions are in effect or if the user is holding Utility Umbrella, 2/3 of its maximum HP if the weather is or , and 1/4 of its maximum HP if the weather is , , Sandstorm, or , all rounded half down.

Healing: stopped by Heal Block

“The user restores its own HP. The amount of HP regained varies with the weather.”
In-game text, Scarlet & Violet

Good to know

Healing move: Heal Block stops it, and Triage gives it +3 priority.Healing moves
Snatch can steal it.
The weather changes it: Extremely harsh sun, Hail, Heavy rain, Rain, Sandstorm, Snow, Sun.