Skill

Skills are customizable abilities for Sonic the Hedgehog in Sonic and the Secret Rings, Sonic and the Black Knight, and Sonic Generations.

Sonic and the Secret Rings
Skills first appeared in Sonic and the Secret Rings where they are unlocked by increasing the power of Shahra's Ring that Sonic wears throughout the game. They can be obtained by increasing Sonic's Level to a certain number by gaining Experience Points (EXP), collecting a specific number of different Medals from the game's missions, or by obtaining a certain type of Medal from a single mission.

Most of the Skills featured in this game fall under certain categories, such as Action type, EXP type etc. which is marked by the Skill Icon next to them. These icons displays the Skills attributes' and their effect:
 * Arrow Icon: Increases Sonic's speed.
 * Wing Icon: Improves Sonic's movements, such as when he performs attacks.
 * Shield Icon: Helps protecting or aiding Sonic when taking damage.
 * Skull Icon: Improves one of Sonic's abilities at the cost of creating a drawback.
 * Ring Icon: Increases Experience Points.
 * Rocket Icon: Increases Sonic's acceleration.
 * Starburst Icon: Exclusive for Crest Skills. Increases the power of the skills of the same element, with an additional effect.

In addition to the categories above, most of the Skills are further classified under three additional Element Groups, which is signified by the color of the Skill Icons. These categories seperate the Skills into more general concepts: The Skills that are advailable at the beginning do not belong to any category or element. The number of Skill Points Sonic has in this game starts at a set amount and increases the more his level rises.
 * Red: Element of Fire, which focuses on attack power.
 * Blue: Element of Wind, which focuses on speed and maneuverability.
 * Purple: Element of Dark, which focuses on miscellaneous abilities.

Sonic and the Black Knight
In Sonic and the Black Knight, Skills are not only used by Sonic the Hedgehog, but also by Sir Lancelot, Sir Percival and Sir Gawain during the second half of the game.

For Sonic, Skills are unlocked (expect for Soul Surge) by increasing the Proficiency Level of his combat styles, namely Knight Style, Cavalier Style and Paladin Style. For each level that Sonic's equipped combat style increases in, he acquires one or more new Skills for that combat style for him to use. Also, if Sonic acquires an upgraded version of an old Skill, which is signified by the sign "+" followed by its rank, the former Skill will be replaced by the updated Skill. Some Skills, however, requires that Sonic has achieved a certain title before it can be used, even if the players already has unlocked the Skill. For Lancelot, Percival and Gawain, the Skills they acquire are determined by the weapon they are equipped with: each equipable weapon in Sonic and the Black Knight has a certain set of Skills tied to them, and by equipping a weapon to Lancelot, Percival and/or Gawain, they acquire the Skills tied to the weapon in question. Unquipping the weapon and switching it out with another, however, will cause all of the character's current Skills to be switched out with those belonging to the new weapon. Both combat styles and weapons can also possess exclusive Skills for themselves that cannot be acquired by either other combat styles or weapons.

Unlike most the games where Skills have appeared, the Skill sets in Sonic and the Black Knight that the combat styles acquire automatically as they level up, and the Skill sets that are tied to the weapons, are not customizable. That means that each Skill set for both combat styles and weapons are permanent, and that players cannot switch Skills between combat styles, between weapons, or between cobat styles or weapons.

Sonic Generations
In Sonic Generations, Skills can be unlocked if you can find all the Red Star Rings in an Act, or can be purchased from Omochao's Skill Shop using points the player earned from each stage. Certain skills can only be used for Classic Sonic, while there are some only meant for Modern Sonic. There are also some that can be used by both. Both Classic and Modern Sonic are at the start of the game given 100 Skill Points to distribute. This number of Skill Points will neither increase decrease over the course of the game.

Trivia

 * The Blast Off skill in the console/PC version of Sonic Generations is similar to the free boost-giving move available in the Wii/PS2 versions of Unleashed.