Short answer: a custom bitmap font, hand-drawn pixel-by-pixel at Game Freak for the original Game Boy cartridges. It never had a public name and was never released as a downloadable file. If you want to use it today, you need a recreation built for modern computers, and that's what Johto Mono is.
In 1996, Pokémon Red and Green were built for a screen 160 pixels wide with three shades of green. Memory was scarce, hardware was scarce, and the body text running through the game lived on an 8×8 grid drawn by hand. There was no separate "font file" to ship. The glyphs were bitmaps baked straight into the cartridge's ROM. The designers never named it because it was never something you'd license. It was an art asset, the same as a sprite.
That's why if you search around for "the Pokémon font" you'll find ten conflicting answers and zero downloadable files. The original is game data, not a typeface.
Johto Mono is a hand-drawn pixel font built to look exactly like the Game Boy era, including Pokémon Gold, Silver, and Crystal. It's a real OpenType font (OTF, plus WOFF and WOFF2 for the web), with 600+ glyphs: the full Latin alphabet, hiragana and katakana, the cryptic Unown alphabet, numerals, ligatures, game symbols.
It's drawn at the same 10-pixel grid the original games used, with the right kerning and ligatures. So when you type in it, it doesn't just look like a pixel font. It looks like Pokémon Gold.
Different font. The swoopy title-card lettering on the Pokémon logo is Pokémon Solid, a display font Nintendo of America had drawn for the brand. Johto Mono is the in-game body font: dialog boxes, menus, battle text, everything you actually read while playing. If you need the logo, you need Pokémon Solid. If you need the rest of the game, Johto Mono is it.
Install it on Mac, Windows, or Linux like any other OpenType font. Embed the WOFF2 on a website with @font-face. Drop it into Godot, RPG Maker, Unity, or Unreal. Use it in Canva, Figma, or Photoshop. Type at 10px (or any multiple: 20px, 30px) for the sharpest result, disable anti-aliasing, and you're back in 1996.
We also built two free tools for it. The Pokémon font generator renders your text in four Game Boy display styles. The Unown alphabet converter turns plain text into the cryptic Unown alphabet from Gold, Silver, and Crystal. Both render in the real Johto Mono, so you can try before you buy.
All four games used custom in-game bitmap fonts drawn by hand at Game Freak for the Game Boy's tiny pixel grid. They were never named, never released as font files, and never licensed. The shapes are part of the cartridge's art data.
Johto Mono is the modern recreation of that original in-game style. A real OpenType font you can install and use today. The original Game Boy font itself was unnamed; Johto Mono is what you reach for when you want the look outside the cartridge.
Different font. The swoopy title-card lettering on the Pokémon logo is Pokémon Solid, a display font Nintendo of America had drawn for the brand. Johto Mono is the in-game body font for dialog, menus, and gameplay text. Not the title logo.
No. The original was never released as a font file. It only exists as bitmap data inside the cartridges. Anything advertised online as 'the real Pokémon Game Boy font' is a recreation. Johto Mono is the one we built.