>>9296420These kits are mostly based on 3mm joints and, in terms of proportions, limbs have been easily swappable with HG Gunpla kits since the days Shinkis were the only game in town.
All lines have their own customization support, with only the Volks Primulas using an off-brand +-shaped peg system for external armour bits instead of the standard round pegs. Koto and Bandai stuff should be a lot less bothersome and cheaper, but Volks has a really good line of hair options that´s close to being on par with the Assault Lilies.
So you can basically switch limbs between all girl lines with little to no issue and use gear and limbs from Bandai´s 1/144, Koto´s 1/100 and even from Robot Spirits figures. Shinki armour bits should work as well.
Swaps with Figmas will pose more of a challenge as they´re individually scaled to the character sheeths, so their faces and limbs will be much more slender than those of plamo girls.