2003 Knuckles seems to be an interesting deal, as his accessory, the Egg Pawn robot is actually likely to be a full-fledged figure, rather than a 'satue' like the other figures have, that isn't pose-able.
Knuckles & Eggpawn box card art features the spectacular loops seen in Sonic Heroes Seaside Hill Area.
Photo by Taaron
Photo by SonicToast
Egg Pawn: The Egg Pawn came with Knuckles. You can move the shoulders but not the legs, so it's a slightly articulated figure. The sculpt is good too, & they used glossy paint on the black portions to imitate metal, which is a nice touch. This figure stands up well. Look at the bottoms of the feet, they're quite well detailed too.
Photo by Taaron