After you use the Pocket Cucco to wake up Talon in Kakariko Village, return the bird to the same red-haired lady who gave it to you. She will give you Cojiro, a rare blue cucco, in return. This starts the trading game.

   

Take Cojiro to the Lost Woods and go left from the entrance, into the area where the Skull Kid used to be. Instead, you'll find the Cucco Lady's brother sitting by a tree stump. Give him Cojiro, and he'll give you the Odd Mushroom in exchange. You must take this item to the old woman at the Kakariko Village Potion Shop within the time limit, or else you'll be sent back here to try again.

   

If you get the Odd Mushroom to the old woman in the Kakariko Village Potion Shop in time, she'll make an Odd Potion from it and give it to you. She instructs you to take it back to the man in the Lost Woods.

   

When you get back to the Lost Woods, you'll find that the Cucco Lady's brother is gone. A Kokiri girl is in his place and explains to you that he turned into a Stalfos. Offer her the Odd Potion and she'll give you the Poacher's Saw in return.

   

Take the Poacher's Saw to Gerudo Valley and give it to the leader of the carpenters, who is standing just outside a tent near the entrance. He'll give you the Broken Goron's Sword in exchange for it.

Scale Death Mountain to the very top and you'll meet Biggoron. Give him the Broken Goron's Sword and he'll give you a Prescription for his eye problems.

   

After you've thawed King Zora, give him the Prescription and he'll give you an Eyeball Frog. You will need to take this to the Lakeside Laboratory, but you only have three minutes to do it. Move quickly, and you can't warp.

   

If you make it to the Lakeside Laboratory in time, give the Eyeball Frog to the scientist. He will give you the World's Finest Eye Drops in return, but once again there is a time limit. You have four minutes to get them to Biggoron.

If you make it back to Biggoron on time with the Eye Drops, he'll give you a Claim Check. Return in three days and present the Claim Check to Biggoron to be rewarded with the Biggoron's Sword.