Complete the "Catchin' Lilipeas" quest and have a saved game from Chocobo Racing on the same memory card as the one used for Legend Of Mana. Enter the save screen, highlight the Chocobo Racing file, then exit out of the save screen. Go to Polpota Harbor. On the Polpota Harbor map screen Skippy, the thin big eared creature from the "Catchin' lilipeas" and "Huntin' Du'cate" quests, will appear and hand you a ring item called "Fastest Wheel".
Get a Chocobo
To get a Chocobo as a pet, have a saved game from Final Fantasy 8 on the same memory card as the one used for Legend Of Mana. Enter the save screen, highlight the Final Fantasy 8 file, then exit out of the save screen. When you catch a bird egg in the eastern section of Domina it should hatch into a Chocobo.
Land Bopper mini-game
Get nine lands in full view on the world map (which should resemble a slanted tic-tac-toe board). Then, hold L1 button for approximately four seconds to get the Land Bopper start screen to appear.
Monster eggs
The most common places for monster eggs to appear are locations which had Boss battles. If when you enter a recent battle area and a monster egg is not there, leave that room and return until one appears. When you find one, map out the most common areas that the monster eggs wander around and leave food every place it usually goes. Note: You can only have five pieces of food out at a time.
Rename items
While on the menu screen, enter the equip menu. Select the item of your choice, select the status of the item, and press X(2) on the item. A name creation screen will appear, allowing you to enter the name of your choice.
Secret sword
Have a saved game from SaGa Frontier 2 on the same memory card as the one used for Legend Of Mana. Enter the save screen, highlight the SaGa Frontier 2 file, then exit out of the save screen. Enter Bone Fortress and head toward the bridge where you fought the DeathBringer. There will be two skeletons at that location. Approach them and you will fight DeathBringer 2. After defeating it, you will get the strongest sword from SaGa Frontier 2.
Shadow Zero mini-game
Successfully complete the "Jewel hunter" quests (The Lost Princess, The Flame of Hope, Drowned Dreams, The Looking-Glass Tower, The Lucky Clover, Cosmo, Two Pearls, Alexandrite, Flourite, and Tear Drop Crystal). When those events are finished, go to the bar in Domina on Salamander day. You should see a Shadow Zero standing near the counter. Talk to him to play the game.
Get "Fastest Wheel" ...