Duplicate Equipment[edit]
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 until. you run out of Fusion time.
255 Senzu Beans[edit]
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 inventory, you will see that you have 255 senzu beans.
Train Weak Characters[edit]
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.