Dragon Ball Z: Buu's Fury/Glitches

Duplicate Equipment
First, Equip Goku/Goten or Vegeta/Trunks (remove all unneeded equips before) and do the Fusion Dance. As Gogeta/Gotenks, remove the equipment from the equipped character. The Fusion will keep the equips but you'll be able to re-use the equips on another character. This will keep working untill you run out of Fusion time

255 Senzu Beans
During the World Tournament Saga, when Gohan asks Goku to get a Senzu Bean, fly to Korin's Tower and get a bean from Yajirobe. Instead of giving it to Gohan, eat it. When you return, Goku will still give a Senzu bean to Gohan even though he does not have any. When you look in your invintory, you will see that you have 255 senzu beans.

Train Weak Characters
Lure an enemy onto a Save Point with a strong character. Punch the enemy and kill it. Before you earn any experience from the downed enemy, the "Switch Character" menu will come up. Switch to a weak character. The character you switched to will gain the experience.