User can change or shift their own weaknesses allowing them to choose what they are weak or strong against at any time, such as changing a weakness to fire to ice or water and/or relocating ones weak spot to somewhere else on their body. Weaknesses changed can be either temporary or permanent depending on the users skill.
Magus (Chrono Trigger) alters his elemental weakness using Barrier Change.
Son of Sun (Chrono Trigger) can continually shift its weak point into any of the flames surrounding him.
After acquiring Shapeshifting, Sylar (Heroes) was able to shift around the "sweet spot" in his brain, lessening the chances of him dying from having his brain penetrated.
Jitterthugs (Kid Icarus: Uprising) are able to shift their vulnerabilities; when red, they're immune to melee attacks and vulnerable to ranged attacks, and when green, they're vulnerable to melee attacks and immune to ranged attacks.
Due to his Evolution, Rahab (Legacy of Kain) was able to rid himself of his weakness to water, at the cost of having absolutely no tolerance for sunlight.
Incentas (Mega Man X: Command Mission) can switch between three different elements to control and, when he does so, changes his weakness too.
In its exoskeletal form, the Metroid Prime (Metroid Prime) can shift its weakness, becoming vulnerable to the Power Beam, Plasma Beam, Wave Beam, or Ice Beam.
The Emperor Ing (Metroid Prime 2: Echoes) can shift between using light and darkness to attack, and when it does so, it becomes vulnerable to the opposing element and immune to the one it's using.
Due to its unique composition, the Crystal Onix (Pokémon) has shifted its weaknesses, being immune to water and vulnerable to fire rather than the other way around.