If I can throw in an opinion, Maiar should have classes and subtypes, like several people have said above. But, instead of saltwater/freshwater or deep/shallow, it should be more of a Predator/Prey dynamic, where each type is evolving to outdo the other.
Predator Maiar can be your typical shark Maiar (sharp teeth, enhanced sense of smell, Muscular, dumb), or they can be dolphins (Ripped, intelligent, greater standing with the Navy), or even other predators to allow for unique body builds and focuses (Eel, Lionfish, etc).
Prey Maiar would be more inclined towards defensive evolutions or speed and generally have high intelligence as well. For example, a Koi Maiar (Higher intelligence, higher speed, athletic or skinny) or a Blowfish Maiar (Toxic, rapid expansion, Gaunt), or even a Blue Whale Maiar (Higher intelligence, Strongman, taller, very slow).
The point isn't to classify what a Maiar eats (I put Blue Whale in Prey, despite their diet), but to classify it's offensive or defensive traits.
Prey Maiar would be more pacifistic, taking up normal jobs such as alchemists, construction workers, and doctors, where
Predator Maiar would be inclined to take up military or aggressive jobs, such as soldiers, gang members, pirates.
These are just basic templates. I'm not suggesting that the other abilities be taken away, just that the concept of templates be pronounced a little more, with a cultural relationship added. You can have a blind Dolphin Maiar that sees with face tentacles or a Whale Maiar that glows green.
There are other suggestions I would add.
- A Maiar cannot go "Up" in any level, meaning that a Shark Maiar cannot become intelligent (or average) or Strongman, a Dolphin Maiar cannot become Muscular, and a Koi Maiar Ripped. Each type has an attraction, and they should not overlap that often. They can lose abilities, though (Gaunt Whale, Skinny Shark)
- Predator Maiar should be about 6ft at highest and have their weight capped off at 300lb at most. Prey Maiar can reach 7ft if they wish, and have a weight of 400, like Orcs
- Prey Maiar must have a dominating Flight instinct. If attacked, their main priority is escape, not victory.
- Alternative builds should be allowed, but they can't override Predator/Prey limits. (No Strongman Megladon Maiar).
- Maiar should be allowed more colors. Many more colors. I want to see a golden Koi Maiar. A white Dolphin Maiar. Not just a blue blob of evolution shaped like a Cro-Allar or an Orc.
- Maiar should be allowed more abilities than feelers and glow balls. I like the idea above. Prey Maiar that can Shock their attackers. Predator Maiar that can weaken prey with poison. More legs, arms, eyes. Balancing is going to be needed, but Maiar should be a seething bowl of creativity instead of a printer creating an Orc with blue ink.
- Maiar should not be allowed defensive plating. No Tortoise Maiar or Dunkleosteus Maiar. We don't need a repeat of the Dakkar just yet, and we already have a slightly defensive race (Zu-Allar). If people want more than that, perhaps it's time to revive Torrp, but we really don't need Maiar to become our tank race. Scales or blubber should be as far as it goes.
I'm playing with the idea of Alpha Maiar in my head. Maiar that break the limits and do whatever they please, but is locked behind Trustee. Not to sure of how that would go, but the concept was inspired by the Cro-Allar and how they lead the other Allar. I feel that Maiar should have some kind of designated leader.