The Professor's Assistant: When Professor Shaia asks you to find his assistant don't. Don't go find him, don't even enter the Deep Dungeon. Instead, go to the Tower of Light, where you would fight Amon's servant a little later. Fight your way to the top, and instead of fighting Amon's servant and getting the Light Key, he won't even be there. Neither is the Light Key. Check the treasure chest and you'll find a Might Helmet.

The Purple Newt: When asked to fetch a purple newt for the "Wizard of Taste", instead you can simply win a grilled newt from any battle and give him that instead. It will have the same effect.

GAME GENIE CODES:
No charge for purchases in some shops: 95A8-67A4
No HP lost when moving in toxic marsh: DDB8-6FD9
Gain six digit experience and enemies leave Might Shield: D2E2-0469
Gain six digit experience and enemies leave Zirco Shield: 05E2-0469
Gain six digit experience and enemies on Doom Island leave Might Bow: 5FE2-0469
Enemies leave Might Armors 70% of time: 58E2-0469
Get high experience and enemies leave equipment 70% of the time: 52E2-0469
Gold Orcs leave Might Swords 70% of the time: 64E2-0469
Efreets leave Might Bows: 69E2-0469
Immune to all status effects: 6D8F-0DC4
Unlimited hit points: 8236-0F34
Unlimited magic points in battles: 823A-0FC4
Gain level after each fight: AAE1-7ED5
Enemies give 30,000 experience points: EA3E-7EE5

Gades Blade: This blade can be found outside of the ancient cave. To get it you must defeat Gades the first time you encounter him. To do this, the best way is to do some MAJOR level building before you face him.

The Egg Dragon: Once you are given the option of fighting the egg dragon, make sure you are properly armed and ready. It is, in my opinion, the most difficult battle in the game. The fight will last rouphly 30 minutes so make sure you have the time. The dragon attacks with fire based attacks (ie. Sunny Side Up) that can hit your whole party for 400 points of damage or higher in some cases. To give yourself a fighting chance here are a few tips:
Get the Apron or Flame Shields from the Ancient Cave and have them equipped. They provide protection against attacks and fire based attacks
Have Maxim and Guy equipped with the Dragon Swords from the casino on Forfeit Island. They are extra effective against dragons (as the name implies)
Your characters should be at least level 80 - high HP levels are important
Champion and Valor are very handy spells to have
In case you hadn't guessed, fire oriented weapons and spells would not be very effective

GAME GENIE CODES:
Attack power, Strength, Defense up to 999: DDE0-DDDD
Level 99 after one battle: 6EEB-DDDD
Opponents always miss: EEE7-4FD5
Kill enemy with one hit: EEE7-44D5