>>45511971>>45512097Regieleki and Regidrago may not be a part of the original trio, but they're still related to them because they're also creations of Regigigas. As I said though, their concept is a mess.
The original Regis are, at their most basic, golems made of solid materials. The idea makes sense and the three feel like a thematic trio because of that consistent element.
The new Regis, on the other hand, are apparently supposed to be golems made of energy. This already doesn't make much sense, and the concept of energy beings would've been better served with an entirely new, separate group of legendaries, but then it seems like Game Freak didn't even have faith in the idea themselves because only Regieleki actually does anything with it. Regidrago instead just goes off the rails, not only making up a completely fictional kind of energy to justify it being Dragon-type but also taking said fictional kind of energy and giving it solid form, completely defeating what seemed to be the point of the new duo in the first place.