>>58955016She's been showing the same amount of skin since at least 1998.
>Red and BlueHer R&B in-game sprite is the only time she's seen wearing the full two-piece bikini and pool slippers (outside of the anime). Sugimori's art for the game gave her the bikini bottoms, but changed the top piece into a crop top.
>YellowIn Yellow, her in-game sprite is essentially her LGPE outfit. In the concept art for that game, it's shown that underneath her crop top and shorts, she's wearing a red bikini top with a water drop emblem and short red shorts. There's a note that reads: "The innerwear is a first-generation style swimsuit". Sugimori's art for Yellow gave her a yellow crop top with a water drop emblem, short yellow shorts, and sneakers.
>FireRed and LeafGreenIn FRLG, her in-game sprite's wearing a blue crop top, blue shorts, blue wristbands and sneakers. Sugimori's artwork matches this.
>TCG and Game Freak website artEven more variations and combinations.