Note: Only use these if you OWN the rom. Otherwise, it is illegal.
Press Open a ROM file from URL -> Insert Link of ROM
Rom Links:

Kaizo (Asshole) Mario

Kaizo Mario World (SNES)
Kaizo Mario World 2 (SNES)
Kaizo Mario World 3 (SNES)

NES

Super Mario Bros (NES)
Super Mario Bros 3 (NES)
The Legend of Zelda (NES)

GameBoy

Pokemon Red (G1) (GameBoy)
Pokemon Crystal (G2) (GameBoy Color)
Pokemon Sapphire (G3) (GameBoy Advance)

SNES

Super Mario World (SNES)
Chrono Trigger (SNES)
Legend of Zelda: A Link to the Past (SNES)