While the PS2 version is the most popular, you may also see searches for a "Wii Budokai Tenkaichi 4 ROM." The Wii version of BT3 used motion controls, and the modding community has ported many BT4 features to the Wii ISO as well. However, the PS2 version remains the most stable.
This project is a ROM hack—a modified version of the original Budokai Tenkaichi 3 ISO file. The team behind it has: Dragon Ball Z Budokai Tenkaichi 4 Rom Download
Over 180 characters at launch, covering Z, GT, Super, and Movies. While the PS2 version is the most popular,