You should get paralyptic hold, it can be useful as an opening power or just if you need to take someone out of the fight for a bit or give a better chance or running out of there alive 
Poison gas, most pets have AoEs so they render this poer useless, and its a PBAoE so you have to go into the mob, which is bad as MMs are pretty squishy.
Noixous gas is very useful if you want to take out Heroes/AVs, it will make your enemies much easier to kill, and they wont kill you as easily. Your jounin are melee so that helps.
I'm approaching the point where I'm going to start getting some of the higher end powers in my secondary and find I don't quite have room for them all. So, comments on which of the following are good/bad/indifferent would be very gratefully received.
Paralytic Poison - a hold and currently I am working on the basis of taking this power.
Poison Gas - Wasn't planning on taking this one.
Noxious Gas - Not sure about this, but sound like it might be worth having.
As I say, any feedback greatly appreciated. If it matters btw, my primary is ninjas.
Skimpy