There is a well-known exploit to effectively have "infinite" stat-improving items like Power Gloves or Speed Rings without using a GameShark: your game.
If you are using a specific slot modifier (like 801B82B4 ???? for the Hero's first item slot), use these hex values to get rare items: Golden Hammer (essential for maxing weapons) 1D: Blinking Mirror (teleport back to castle) 4F: King Dragon Sword (Hero's strongest weapon modifier) 23: Suiko Map (reveals world map) 15 – 1B: Stat Stones (Power, Magic, Speed, etc.) Important Precautions
Go to your item menu and highlight an item. Press Right to cycle that slot through the game's entire item list (e.g., changing a "Medicine" into "Full Helmet").