As a Pokémon expert, I can tell you that Flail is a move in the Pokémon games that is used by a Pokémon in battle. It's a physical attack that is determined by the user's HP. The more HP the user has, the more damage the move will do. However, it's important to note that Flail's damage is not fixed and can vary. It's calculated as follows: `(20 × (user's current HP / user's maximum HP))`, which means that at full health, Flail does 20 damage, and at 50% health, it does 10 damage, and so on.

Here's the translation in Chinese:

作为一名宝可梦专家，我可以告诉你 Flail 是宝可梦游戏中的一个招式，由宝可梦在战斗中使用。这是一种物理攻击，取决于使用者的HP。使用者的HP越多，这个招式造成的伤害就越大。然而，需要注意的是，Flail的伤害并不是固定的，而是可以变化的。它的伤害计算公式如下：`(20 × (使用者当前HP / 使用者最大HP))`，这意味着在满血状态下，Flail会造成20点伤害，50%血量时会造成10点伤害，以此类推。

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Flail can now cause a critical hit, and its damage is now varied by a random number during damage calculation. Flail can be used as part of a Pok��mon Contest combination, with the user gaining an extra appeal point if the move Endure was used in the prior turn.read more >>