Random Name:
When asked to enter a name, press L1 + R1 or L2 + R2 to choose a name at random.

Random Teleportation Trick:
When you get Viki in your group and ask her to teleport you somewhere, once in a while she will teleport you in the wrong place. One of which is a hidden room in Radat town. Here you'll find many nice items.

Best Ending:
You must have all 108 stars before Kiba attacks Viktor's old fortress. When you return to Rockaxe Castle and after your fight against Gorudo when Nanami gets shot by an arrow, she will ask you to call her "big sister" for one last time. Now you will have to do this fast, do not read the lines anymore, just keep on tapping the confirm button until the conversation is over. When you arrive back at your castle, Dr. Huan says that she will be ok. Then after you beat the final boss, the Beast Rune, go to Tenzen Pass and to the place where you promised to meet Jowy at. When you arrive there you will find Jowy. Jowy will challenge you to a dual battle. When it starts, do nothing but defend until the three fights are over. When Joey offers you the Black Sword Rune, do not accept it. The ending is still the same except the final picture which is different.

Cool Stuff Early:
You can push the door in Muse-Matilda border open and get all the cool stuff early. Just don't get Humpfrey and Futch of else you'll lose them later.

Thanks to Revolution readers Jason Sommerfield, tetsu_1_ 2000 and Jan Aldrin Ramos!