[@Raineh Daze]

It's flexible. A part is just a segment of your mech that defines it, by either being an actual body part or a weapon/gadget. It acts as a physical location on your mech and grants you abilities. 

Like with mine I had the obligatory head part which lets me attack, wings as a movement element that lets me fly fast, and for the sake of simplicity I merged both the torso & legs and the various guns into their own parts. The torso/legs basically being for tanking the majority of damage and some slight utility and obviously the guns being another method of attack.

Like say with the basic ass gundam Rx-76 would be like:

Head: attack(head vulcans), useful.
Backpack: useful.
Body: defense.
Legs: useful
Weapons: attack

Or something along the lines.