The Link Patch is based it when Mario or the other players get the Master Sword in the Super Mario Maker 2 game, my main ideas from the patch are the following next:
-Link as a player with the original and only Super Mario Bros version graphics
-Alternate graphics for Super Mario World or Zelda - A link from the past
-Link with the Sword, Arrow, Shield and Bomb with abilities, which are adapted with the Snes controller based on the Mario Maker 2 (One part with all the powers and the other part of the patch, some powers must be unlockable after defeat the boss or earned in some places or whatever)
-Aditional powers, fire(Like the game triforce heroes), and the grabar object, etc
-Life bar if Link gets hurt, he loses life depending the enemy
-If he loses all lives the animation must be like the zelda games instead mario lost screen animation
-An aditional patch that the boss show the Life bar, also if the boss is defeated link will earn one life
-An aditional midway bar based on the zelda games
-An aditional goal point
-Link with the overworld screen
I'd kill for "Link in Super Mario World" to be a thing, not to mention the Zelda based SMW romhacks that might follow. To me, new characters that play different from the default characters are one of my favorite kinds of hacks, the Sonic hacking community has been amazing at porting new characters to old games with their abilities intact.
Maybe if someone gets Link done we could be one step closer to a console compatible port of Super Mario Bros. Crossover.