Jump higher with Morphball (demo version):
Go into Morphball mode and remain absolutely still. Set all bombs down quickly. Once the bombs explode, immediately change to normal mode. You should jump even higher.

Super Missiles (demo version):
In multi-player mode, get as much of the energies (weapon energies) as you can, then get a the missile. Once obtained hold Fire (when you select the missile icon so that you have missiles) and you will start charging with the missiles.

Charging rocket launcher (demo version):
Obtain the red missile icons two times (in multi-player or single player mode), then hold or tap and hold Fire.