Agreed. I’ve actually come up with a few more species that could be introduced as well (whether still living or extinct). I have them listed in the Rahi section of this topic:
Energy Hounds: same as G1, but possessing adaptive biology to survive their immediate surroundings.
Kanohi Dragon: legendary Rahi (extinct?) possessing a variety of unnatural abilities, which is further explained in the link.
Visorak: spider-like Rahi possessing near-Matoran sentience. Venom can cause induced aggression and ferality. Amphibious and omnivorous.