GOKAAAAI... SILVER!
The Kirby games I’ve managed to 100% clear are:
Adventure (NES)
64 (N64)
Nightmare in Dream Land (GBA; this one only happened very recently, actually)
Amazing Mirror (GBA)
Squeak Squad (DS)
Super Star Ultra (DS)
Return to Dream Land (Wii; this one’s only a technicality since I cleared 100% of both Normal Mode and Extra Mode as well as the regular Arena, but I still have yet to beat the game’s True Arena)
Triple Deluxe (3DS)
Strangely, the Hammer’s Hammer Flip move seems to have a much shorter range in the original Super Star compared to Super Star Ultra, so I’ve yet to beat The Arena in the original Super Star. And for Dream Land 3, the most I’ve gotten is 97%, since I never beat the Boss Butch, the “Jumping” minigame, or the “Super NES MG5” mini-game rush mode.