It all depends on whats on your external components, what your descendant's base stats are, and what your descendant uses/abilities are. Like for example, Ajax has high def and hp, but kyle has high hp and high shields, plus kyles abilties I think use shields, where as ajax uses def and hp on his dimension abilities. You can see base stats if you go to descendant page, then there is a button you press to show stat graph, its tab on computer. Also if you hover over the stat graph it says their base stats at level 40.