This article is incomplete. Please feel free to edit this article to add missing information and complete it. Reason: Needs clarification on whether failure glitch occurs in the Japanese Pokémon Stadium.
Softboiled restores up to 50% of the user's maximum HP. It will fail if the user's current HP is already equal to its maximum HP.
In the Generation I handheld games, Softboiled will also fail if the difference between the user's maximum HP and current HP is 255 modulo 256 (i.e. if this difference is 255 or 511). This does not occur in Pokémon Stadium.
Generation II onward
Soft-Boiled no longer fails if the difference between the user's maximum HP and current HP is 255 modulo 256.
If powered up by a Normalium Z into Z-Soft-Boiled, all of the user's lowered stats are reset.
Outside of battle
Prior to Generation VII, Soft-Boiled can also be used outside of battle to transfer some of the user's HP to another party Pokémon. Each use will transfer 20% of the user's HP, up to the target's maximum HP. The move will not work if the user has 20% or less HP left.
The egg in Chansey's pouch glows yellow and it raises its arms into the air. When it does, a yellow glow in the shape of Chansey's egg rises from its pouch into the air. It then floats over to the target and melts into its body. As it does, the target's body becomes outlined in yellow, healing it.
Male Pokémon can use this move despite its Japanese name being タマゴうみ Tamago Umi, which can be translated to "egg lay".
In Generation III, the status screen erroneously states that the move has 100% accuracy, even though it targets the user (thus it ignores accuracy and evasion checks).
In Generation III, if this move is used immediately after Brick Break, the egg that appears will be transparent rather than solid. This is only a graphical error and doesn't affect the execution of the move.
In the 1.0 release of the English versions of Pokémon Ruby and Sapphire, whenever the player uses Softboiled on a Pokémon that is fainted or at full health, the game erroneously states "This item can't be used on that POKéMON." In the 1.1 release, the word "item" was removed and the message correctly says "This can't be used on that POKéMON." This error does not exist in the Japanese versions, meaning it was a localization oversight.
Of all TM moves, Softboiled is learned by the least Pokémon.