B'Boom's beast form is designed to rest on all 4 legs though he can stand on just the rear ones. The rear legs bend at the ankle & knee, turn bellow the hip and are ball jointed at the hip. The front legs have a ball jointed ankle, bend at the elbow, swivel bellow the shoulder and have a ball jointed shoulder. This articulation will be carried forward to the legs and arms of the beast mode respectively. If you pull back on the ears of the toy the mouth and eyes open. There's also a lever in the back of the toy which can then be slid forward to expose the gun and both missiles in the mouth.
To TF to battle platform mode: Pull the sides of the underneath of the body down and fold to the sides. Pull the head forward. Fold the back of the head and all the back of the toy back from the back of the toy folding the waist under the toy. Fold the feet back so he's standing on the top of the beast feet and flip out the heel spurs. Fold the far end of the sides of the undercarriage out, push the lever on each of these forward so the guns extend and position (via some joint origami that I won't even attempt to describe) along side the big gun in the middle of the toy - TFU's photo has the molded missile arrays pointing up but I'd fold them to the sides extending the surface of the battle platform and getting the folded down flaps underneath.. Fold the beast arms/forelegs under these - these can be folded down to help stabilise the toy. Slide the big gun forward using the small blue lever on the back - the trigger is now exposed and it can be used as a missile launcher.
You know for ages I couldn't stand this mode - bit of a mess, odd 3rd head sticking out the front, not stable. But today I just happen to have my box of RID Spychangers by the PC and B'Boom's attack platform is perfect to use with them - or Legends/Micromasters ! Something similar at the time would have enhanced the toy no end !
TF (from beast to robot) Turn the rear legs round 180 degrees bellow the hip so the grey is on the outside of the legs and the blue is on the inside. Straighten the legs behind the beast. Fold the foot out so the top of the beast foot is underneath. Fold down the heel spurs. Look at the bottom of the beast. Fold back the end of the under carriage panels. Fold the ends down. Swing round 180 degrees via the ball joint they're attached to. Fold the gun panel out to the sides 90 degrees. Swing the gun panels up and lock onto the sides of the chest with the missile arrays facing out. Fold Mandrill head down onto the chest, then pull the entire chest panel down.
Resulting robot retains all the poseability outlined in the beast mode, plus a ball jointed head. Again he's reminiscent of Primal with the mapping of beast to robot legs and the simian face ending up on the robot chest. The guns on the side of the chest can be raised still - though the slider is within the chest - as can the main gun & missiles which are now on the back. Gun can be removed and used as a handheld weapon.
Overall: Beast and robot mode derived from larger and better toy. Odd third mode that couldn't be used to it's fullest extent at the time due to no smaller toys. You won't find a huge amount of love for him floating around, but give him a try with some smaller TFs in Battlestation mode.