Oh. So what other relatively powerless species are there? (And also, what about all those other humans in the character list?)
In a technical sense, there aren't any "powerless" species per se. Brain-power kind of counts as a "power", which is why the knowledge stat is so important. In Imagni's case, having that sort of brain power gives him limitless possibilities to self-created weaponry. Tech has never versus magic before, so one can't say light-powered missiles and lasers won't have an effect on ghouls and goblins if you catch my drift.
Although if there were a category I would place Imagni, I would say about the same as this guy:
Dr. ClaudeEhhh, well... Wizards are more so on magic, but this guy in particular favors science. There are a number of things you can choose, but half-humans are allowed in 2100:
http://en.wikipedia.org/wiki/List_of_species_in_folklore_and_mythologyAnd sure, if you can find a fitting constellation, go ahead and give it to Imagni. I have no idea which ones are left myself...
These are all that's left:
* Volans (The Flying Fish)
* Aquarius (The Water-Bearer)
* Musca (The Fly)
* Taurus (The Bull)
* Puppis (The Poop Deck)
* Cepheus (King of Ethiopia)
Also oh god those special moves are powerful. Coming up with a moveset for Imagni is going to be a lot of fun.
Take your time on them. In all honesty, seeing a full-fledged list would be awesome. Try to keep it balanced too. Most of the moves, like the one-hit-kills are
Guilty Gear /
Blazblue inspired so even if a character is really powerful or weak, this is a game so it's obvious there's gotta be a balance for the sake of gameplay itself. Also, I imagine Imagni entering a stage from a rope-ladder from his castle (as if coming from a helicopter), placing the background with walls (with integrated cannons), and fighting somewhat like this guy:
More or less like him. You get the idea. He uses a gun too

Btw, if you have a 360 or a PS3 or ever get one (or know a friend who owns either and is a fighting-game fan), you should definitely try out Blazblue. It's really awesome. I'm sure you'd identify its characters and easily see which 2100 character best represents the Blazblue cast. I've always compared Ragna to Karoku and vise versa. I think Carl Clover and Imagni compare a little too (just a little).
Your one-hit-kills with yourself and your tag-partners can be as crazy and chaotic as you want. That's the beauty of 2100. It's full of ungodly mayhem.
Although to see what I mean, I imagine Imagni's castle being involved this way:
http://i50.tinypic.com/2wco7lg.jpghttp://i49.tinypic.com/6psx1e.jpgBoth pics are edited with the cannons I drew on Imagni's drawing. It'll give you an idea of what I mean. Given the castle can do a number a things, spreading its walls into columns in that formation can make for an interesting move-set, and depending on the position/angle Imagni is facing, the cannon closest to him will fire. Besides, having control over so many cannons is tedious, so it's obvious the cannons are sort of remote-controlled based on where the player has Imagni positioned. The cannons that appear big are the closest to the player screen while the farther ones are in the background.