The G-Element is, of course, heftier than the Elements in their individual gears. Although things like frame durability and ether induction stay the same, its overall strength is twice what any of the girls could do on their own, and it dwarfs their other gears - as well as those of their chosen opponents.
Bladegash comprises the external components -- hands, legs and feet, head, etc., Grandgrowl is the torso, Marinebasher takes the place of lower torso and legs, and Skyghene provies the top and final portion of the gear. (I wish I could provide a better example, but describing the diagram would only confuse both of us. ^_~ It's a shame the pic is cut in half across two pages, or I'd have scanned it.)
I can't say when the four girls learned to merge their gears this way, but I think all Elements, with the inherant closeness of such a group, have a similar sort of attack, in their time. The four must have complete trust in each other in order to merge their gears in this fashion, and it's demonstrated in the game, when you confront them!
Height: 37 sharls
Weight (dry): 55.0 karn
Weight (equipped): 69.0 karn
Sub-Generator Torque: 1600
Main Generator Coefficient: 4.3
Battery Life: 450 zeitle
Frame Durability: 300
Reaction Time: 1.2
Ether Induction: 55
Speed (ground): 180 repsol
Speed (air): 880 repsol
Weapon: installed vulcan gun, burst knuckle (?), -2 I didn't recognize.