From Bulbapedia, the community-driven Pokémon encyclopedia.
This is a list of Pokémon by their call rate. Pokémon with the highest call rate of 15 are most likely and most successfully to call for help during SOS Battles, while Pokémon with a call rate of 3 are least likely. Pokémon with a call rate of 0 will never call for help; notably, this includes all Legendary Pokémon, all Ultra Beasts, all Pokémon encountered via Island Scan, and all Pokémon encountered in Ultra Space Wilds.
This list only includes Pokémon that can legitimately encountered in the wild in games with SOS Battles.
List of Pokémon