Ninja - melee offense. Some late control with the Oni.
Robotics - ranged offense. Some healing and defense with Prot Bots.
Neromancy - melee offense. Some control with the Lich and Spirit.
Merc - ranged offense. Some control with the Spec Ops and healing/status prot with Medic.
Thugs - ranged offense. Some buffs (defense, damage, accuracy) with the Enforcers.
Does anyone made a list yet with all the details of each attacks for each henchmen? Not as in the list you've made in your guide already, but details such this attacks does -def this one -jump ect ect.
Not familiar at all with ninja or zombies, but mercs and robots become AOE mayhem and destruction after 32 
[ QUOTE ]
Ninja - melee offense. Some late control with the Oni.
Robotics - ranged offense. Some healing and defense with Prot Bots.
Neromancy - melee offense. Some control with the Lich and Spirit.
Merc - ranged offense. Some control with the Spec Ops and healing/status prot with Medic.
Thugs - ranged offense. Some buffs (defense, damage, accuracy) with the Enforcers.
[/ QUOTE ]
Thanks a lot for the help 
Yup Master_Zaprobo is pretty much the mm guru it seems. One thing I would add is thugs (when they come out on live) have a short range nasty in their last pet. Much like the ninja's get control with theirs.
But still, primarily ranged damage and, to be honest, damage in general. 
Friends are just enemies that haven't betrayed you yet.
Using Enhance Minion on Undead gives their vomit a good deal of ranged damage...mines only lvl 12 and quite happy mixing it up.
I posted on union villains but figured that was the bad place so here it is :
Hey there, i'd like to know the difference between the different pets of the MM... Are some more on attacks, or more buff, or more defence ?
Or there are no difference at all... perhaps ?