Big Waddle Dee, as its name indicates, is an over-sized Waddle Dee. It has no defining traits, attacks, or characteristics to set it apart from regular sized Waddle Dees other than its massive size.
Being only a large Waddle Dee, it meanders about aimlessly, but can hurt Kirby if the two collide. Despite their larger size, Big Waddle Dee does not have significantly more health than a regular Waddle Dee does, making it about as simple to defeat. Big Waddle Dee is incapable of jumping but can fall from ledges.
Big Waddle Dees are orange, three times bigger, and are also immune to Kirby's Yarn Whip (but not his Weight form). A harmless sleeping one appears in Castle Dedede and there is no way to wake it up, hinting at their laziness. Yin-Yarn drops two from the sky as an attack during his boss fight.
Big Waddle Dee appears exclusively in Dedede Resort, most notably in Stages 6 and 10. It carries a giant bomb and lobs it at the Kirbys when it sees them. Its size makes it stronger than many smaller enemies, requiring a mob of Kirbys or several small attacks to be defeated. A Big Waddle Dee wearing a colossal Star Block as armor serves as a mid-boss in Stage 7.
Big Waddle Dees make their return, only appearing in the Dimensional rift levels on Pop Star. They act the same as in Amazing Mirror and Squeak Squad, even being defeated the same ways. Like other enemies, they have a Halcandran counterpart that acts the same as them, being encountered in the Dimensional rift levels on Halcandra.
Big Waddle Dee appears exclusively in EX stages. Like all Waddle Dees in EX stages, the enemy has purple fur. Big Sectra Dees and Spear Big Sectra Dees also appear. Inhaling any of these creatures instantly creates a Blaster Bullet in Kirby's mouth.