First of all, learn Powerbomb and Giant Swing/Giant Spin. 
Also, you'll need the Brainbuster to Kaiten-suichoku-rakka 
(Spinning Sheer Drop) Brainbuster combo. It would also be 
advisable to learn the tie-up F,X stomach punch. 

Build up both the Powerbomb and Giant Swing/Spin to level 50 
(have to hit those moves at least 246 times). The Powerbomb 
will unlock the moves Splash Mountain (in two forms - DFx2, 
A+B from standing, or as a combo from the tie-up stomach punch) 
and the Giant Swing/Spin will unlock the Throw Away Giant Swing 
(from standing HCF [half-circle forward], A+B). 

Combine one of the two Splash Mountains with the 
Kaiten-suichoku-rakka brainbuster, and that will give you the 
Build-Up Buster (from standing 360 degrees on the joystick, B). 

Next, delete the Powerbomb, and learn Piledriver. Combine the 
Piledriver with the Throw Away Giant Swing to get the 
Build-Up-Driver (from standing, 360 degrees on the joystick, A+B). 

Finally, to acquire the ultimate move in the game, the Giant 
Gram (from behind opponent, 360 degrees, B), simply combine 
both the Build-Up Buster and the Build-Up Driver.