From a different topic I got the idea to make a complete list of the weaknesses of the brothers. I don't know everything so please help in completing the list. I'm using the German names.

Mantid:

Strategy: I noticed that you too can drink from the colour globs that appear in the arena. I don't know if you really get that colour added to your memory but at least Mantid won't be able to heal as much. Otherwhise wait for him to drink from the colour and hit him.

Best Glyph: While drinking he stands perfectly still so ritual should work well.

Triumphator:

Strategy: He is a pushover. You only need to find him after he teleports and hit him before he can attack. With a little luck you can win this battle without taking damage.

Best Glyph: I found wasp and hawk to be very effective.

Vormund:

Strategy: It's not very difficult to dodge the groundspikes he throws but when he starts to swing towards you you better be careful because that attack is unblockable and does some serious damage.

Best Glyph: Hawk and owl are the best for this battle because no matter how much he swings, owl will chase him dowm and hawk can be redirected in case you miss.

Montgolfiere:

Strategy: If you can stay on higher ground you just need to dodge his bombs. When fighting him on the ground you need to be careful when he loses a ring because he will do an attack that covers the entire ground.

Best Glyph: Same as Vormund but when you don't think you can dodge his bomb I recommend the shield as well.

Richter:

Strategy: Be careful when he comes out of the ground. When he appears from right below you he can do a lot of damage and throw you to the other end of the arena. Repell is vital for this battle because of the little drills he uses to attack you.

Best Glyph: I noticed that owl works very well against him. Other glyphs can be blocked with his drill projectiles.

Ok that are all the brothers I know the weaknesses from. Please post when you know the best strategy for other brothers or if you have some constructive criticism for my strategies.

The ones I fought:


Ironclad:

Stay midway range from him, hit him with Wasp, Hawk or Owl and Shell agains the 3 projectiles in his last ring. Never get close to the ground turrets.


Mongolfier:

Go to the highest point of the ramp and hit him with a stream of Wasps until he reaches the last ring. In the last ring when you hear a siren Shell and after that resume Wasp bombardment.


Patriarch:

Wasp, Hawk, Owl and Tumbleweed work well, just side steep his attacks and Shell against his blade attack.


Whaler:

Either lure the head away with magnet and bombard him with anything you got or let him reach 3 heads and then bombard him.


Tyriant:

Move around a lot a wait until his trajectory goes over you (he won't damage you if he passes over you). When he is on a strait line with you, Wasp or Sleeper to hit him.

Patriarch - if you have have 100% speed, you can just circle around him, stay close to him and keep yourself behind him all the time - he won't be able to launch any of his attacks - and you can bombard him with anything you like (I used wasp) => win with no damage taken at all

Ironclad - I sometimes used the Magnet to relocate his turrets to one side of the arena and keep the fight at the other side

Triumphator - At the first two rings, he only attacks when you get close to him, so I bombarded him with Wasp from afar. At the final ring, he used an attack that could do damage wherever I was, so i had to rush up to him and finish him as quickly as possible.

Caterpillar - This was the longest and most difficult fight for me. This one has an attack that can push you out of the level, which means instant fail. I stayed behind pillars, constantly moving to stay behind cover, and attacking him from there with Wasp and quickly rushing to cover again. Sometime, he got me with the push attack (which pulls first then pushes) - if I pushed myself into the pillars (pillar between me and him) while he is in the pulling phase, he couldn't throw me off the map - I just needed to stay out of his sight as much as possible. At the last ring, he sends the rock balls after you, but those are easy to dodge and he is stationary while doing it, so I could hit him with Wasp from afar. Another reason to keep distance from him is because he (and the rock balls) simply drain color from you if you get close.

The ones i fought so far.

Warden: I fought with him once when I only had Wasp and couldn't beat him, so I tried after getting de Owl/Hawk and it was really easy.
You have to fill yourself with Azure at 100% or you wont be able to dodge the spikes. But i found Ritual works best for him, 2-3 shots and hes dead.

Whaler: Just blasted him with everything, if you dont defeat him quick, you lose. Wasp until he grabs the three heads, and then a strong ritual will do (35 pts)

Patriarch: I just stood behing him and finished him with Rituals.

Now I'm trying to beat Ironclad because i hate him xD, but he's pretty tough, I run outta colors before finishing him.

I killed Triumphator in one hit with web, because I'm awesome like that. 8) (this is way more trouble than it is worth.)

Haven't used any special strategies for the other ones so far, except
Ironclad: I start the fight by setting up two ritual points of his palette color, then send owls of his wheel weakness after him until his first wheel comes off. Use a magnet of minimum strength (16 drops) to bring all his cannons into a corner so I don't take ridiculous damage from them, and they don't distract my owls during phase 2. Then I play phase 2 like phase 1, hit him with owls of his weakness, once he's down to his palette, I go into a corner, draw the third ritual, and another magnet and hit him with whatever works as fast as I can.

Edit:
Patriarch also went down in a single web, which was much easier to pull off than Triumphator.

You just throwed the web at them?
I still haven't killed Mantid and I was wondering if I could use web on the balls he feeds with.

Web does damage even when the enemy doesn't eat them?

I had a tough fight with Ironclad, but I found Wasp works faster and better. And of course a little green ritual saved for the final ring

When you fire a web and there is nothing nearby for it to latch onto, or it takes too long to latch on, it eventually explodes.
When it explodes, it does tons of damage, but only if it is directly in contact with an enemy.
It is possible to get the web stuck on certain enemies (I have confirmed The Worm, Triumphator, and Patriarch).
Triumphator is really difficult to hit this way, though. Basically I had to just fire it from far enough away that time would run out and the web would explode just as it reached him, or get lucky and get it stuck between his two cymbals.

Basically then you just have to get close to the brother and then wait.
Can you use it several times at the same time, I mean throw 5 or 7 webs together and then wait?

Anyone tried that!?

I tried web on Patriarch, and that worked great -- If you stand next to a pillar, he will wheel to you so close that he's practically on top of you. Then you can cast web and it won't have any place to go. Use shield when he swings his arm up to strike until the web explodes.

I fought Caterpillar next and it seems as if he had a weakness to owls. Just send one fully charged owl after another and stay in cover from his pull/push attack, and you can win without taking any damage.

I tried this with triumphator, but if you use more than one at a time, the others get blown away when the first one blows up.
Anyway, using this method you'll need at most three hits on anything it can work on. (I've only tried it on worm, triumphator, patriarch, mantid, and pit. And it doesn't work at all on mantid or pit, some of the other brothers might be susceptible, though)

Yes, that wouldn't work also because Triumphator keeps on teletransporting all the time.
BUT (and it's a big BUT) it worked perfectly with the Hawk glyph on Mantid.
Since he recovers very quickly, i did this:
I drew 5 or 6 heavy hawks (20-30) and then stroke once he finished sucking colour, this way I managed to get a start advantage over him...

I'm eager now to try it with Pit or Montgolfier...