I know this is long overdue, but I wanted to make sure I had enough to write about before I started this :).
We all know who the M'arrillians are fairly weak jelly fish-like creatures, except for their strong mental abilities. So it is obvious that they are strong in the Water element, and, on average, they have high wisdom.
Before, I said that no tribe is inherently "evil". Well now I take it back. Evil is something that is determined by the majority of a group. With each tribe, everyone has a different definition on what is evil. All of the tribes share the common enemy of the M'arrillians.
I don't feel that the M'arrillians want to accomplish an evil goal, but the way they want to solve their problems is in, as the tribes believe, a completely unacceptable way. M'arrillian chieftains (I specify chieftains because they have hinted towards more subtypes of M'arrillians other than the Fluidmorphers) literally take a creature, and forces them to obey no matter what. We don't know if they also wipe away the creature's memories, or if the creature is conscious and is aware of everything that the M'arrillians are forcing it to do.
There is one Minion that I really think should be pointed out, and that is Tartarek.
Read his ability, and tell me if you can notice something odd about him. When he is a pure Overworld creature, he has the stat gaining ability which is one of the Overworld trademarks. Then he has the ability to destroy Chieftains, which is a very power ability. Now here is the weird part: as a minion, but he keeps his ability to destroy Chieftains. While he is being controled by a M'arrillian, he retains his ability to destroy other M'arrillians.
Why would a brainwashed creature keep his abilities in the first place, much less an ability that is dangerous to the M'arrillians? No other creature can keep its regular abilities, except Tartarek. The only thing that is special about Tartarek compared to the other minions is his incredibly high wisdom and courage. I believe that it is linked to his wisdom. It is possible that he has enough mental power to resist the psionic abilities of the M'arrillians, in fact there isn't a single M'arrillian with more Wisdom than Tartarek.
I hoped that you enjoyed my final (?) installation of the Color Wheel