That’s why I like the idea of most of the many secondary elements being all female except for 2. Fire, air, earth, stone, ice, magnetism and gravity are all male. And water, lightning, plasma, psionics, sonics, iron and plant life are female. It also results in a potential for each element to have an opposite sex counterpart dynamic.
Fire and Plasma for heat.
Ice and Sonics for their mutual preference for quiet solitude.
Air and plant life for their shared jungle and forest preference.
Magnets and iron because that just makes sense.
Stone and Lightning because Stone prefers deserts and massive lightning storms happens a lot in the dry statically charged desert environment.
The rest are a tad odd with matchups like that though.
Water and Psionics don’t really have good matches with Earth and Gravity. Maybe with gravity giving increased resistance to high pressures, Ba-Matoran make good freedivers and the tough male Onu-Matoran are the brawn to the brainy Ce-Matoran nerd girls?
Also if I had control over how a G3 works, the color schemes are all more fluid with how much you can stretch the main schemes. For example, a white and sand green Toa could be Ice or Air or even plant life depending on color distribution and accent parts like a fitting mask power or weapon or elemental furnishing piece.