Triforce of Wisdom
The three pieces of the Triforce are a sacred relic in The Legend of Zelda lore, with legend stating that anyone who collects all three pieces of the Triforce will be able to grant themselves a wish. It is stated in A Link to the Past that the three Golden Goddesses, Din, Nayru, and Farore, left it behind after they created the land of Hyrule, and Hylia was tasked with watching over the land and the Triforce.
The three pieces of the Triforce are spread across the main characters in the series - Zelda holds the Triforce of Wisdom, the left piece; Ganondorf holds the Triforce of Power, the top piece; and Link holds the Triforce of Courage, the right piece.
The Final Smash is very similar to the final battle against Ganon in Ocarina of Time, where Zelda used the power of her Triforce to trap Ganon so that Link can deal the final blow.
In Breath of the Wild, Princess Zelda is said to have a "sealing power" that she has been unable to harness for most of her life, which causes much strife between her and her father. She eventually learns to use this magic. When she uses it on Dark Beast Ganon following the final battle, he disappears in a similar vein to this Final Smash, although it is a bubble shape with the entire Triforce overlayed instead of only a single piece of the Triforce.
Zelda traps her opponent within the Triforce itself, before she launches the opponent away behind her. If their damage is at 100% or higher, the target is instantly KO'd. Its range takes up the entirety of a Battlefield stage. The Triforce itself has a strong vacuum effect and lasts a long time, making it difficult to get away from if players are close to Zelda when she uses it. After the Triforce's summon, the fighters take 7% damage. Additionally, periodic shockwaves ripple the stage, knocking fighters who are escaping the attack, drawing them towards the Triforce. It is often considered to be one of the best Final Smashes in the entire game, as it has incredible range, high damage output, and KO potential at high percents and near the blast zones.