Barrier Shift

Wall Change, also called Barrier Shift or Elemental Shift, is a recurring ability in the series. It is often used by bosses, which changes the bosses elemental weakness while it absorbs all other elemental attacks, and is often used after the player strikes the boss with its elemental weakness at the time.

Final Fantasy III
WallChange changes the user's elemental weakness and allows them to absorb all other elemental attacks.

Final Fantasy V
Wall Change, originally called Barrier Change, is used by Archeoaevis and Omega Mk.II, which allows them to change their elemental weakness at will.

Final Fantasy VI
Barrier Change, originally called Wall Change, is a special ability of several bosses, most notably Kaiser Dragon and Magic Master. Here, it allows the user to be weak to one element, absorb another element, and nullify the damage of all other elements.

Final Fantasy X
Elemental Shift is used exclusively by Greater Sphere and Spherimorph. It allows the user to change their elemental weakness, as well as other elemental attributes to match the weakness, when they take damage.

Final Fantasy X-2
Barrier Shift, used only by Protean Gel, allows it to change its elemental weakness.

Final Fantasy XII
Shift, used by mainly the Espers such as Phoenix, allows for them to change their elemental weakness.