What is the largest legendary Pokemon?

Answer 1

Depends on what you mean by "large". Rayquaza is the tallest legendary pokemon, being 23 feet (23'/7m) tall but is 455 pounds (455lbs./206.5kg).

Giratina, though, is large in both height and weight. It was originally supposed to be 22 feet and 8 inches (22'08"/6.9m) and weigh at 1433 pounds (1433lbs./650kg), but was altered to be 14 feet and 9 inches (14'09"/4.5m) and weigh at 1653.5 pounds (1653.5lbs./750kg).

Edit: I forgot to mention that Groudon could also be qualified as the "largest" legendary pokemon. Even though it is only 11 feet and 6 inches (11'06"/3.5m) tall, Groudon is the heaviest weighing at 2094.4 pounds (2094.4lbs./950kg). It is also the heaviest pokemon ever. Also, Giratina's original stats landed it 3rd for heaviest pokemon after Groudon and Dialga (1505.8lbs/683kg) but its current stats make it 2nd place. Plus, Giratina would've original been the 5th tallest pokemon but is now the 10th tallest along with Kyogre.

Added bonus: Despite Rayquaza being the tallest legendary pokemon, it is only the 4th tallest pokemon. The tallest 3 pokemon are Wailord (47'07"/14.5m), Steelix (30'02"/9.2m), and Onix (28'10"/8.8m).