In CoX, both the Controller and the Mastermind got pets, and I think they both got a defender secondary set. The controller generally got some kind of single target and/or group hold suppression power (immob, slow, repeated knockdown, etc) and had to wait for level 38 to get a pet, which sometimes wasn't really that good (looking at you, Singularity). The Mastermind just got the best pets, and pet upgrades, and a few attacks of their own so they could pretend like they were fighting too (tongue in cheek).
To differentiate the two classes better this time, I think controllers maybe shouldn't get pets. Or if they do, they should get the non-AI kind that just follow you around or are immobile once placed (like the devices Turret, etc), maybe even make them untargettable and somewhat less effective, more rudimentary.
This brings up the problem of what should the controller's "Awesome level 38 power" be, if there is in fact a need for something analogous to that in CoT. well, since the fire imps and whatnot were really just the controllers damage source, you COULD just give them some kind of attack power. It could be a DoT toggle that does like really good damage and had a hold effect that stacks with the other hold powers, it could be an untargetted ranged AoE that you drop like Rain of Fire that does hold + damage, or hold + damage + debuff, etc.
As for the Masterminds, I think their biggest issue in CoX was that they could plow through a mission map at high difficulty/team size settings faster than most other ATs and maybe need to be toned down a little, at least on the higher level end. Low end they weren't really setting the world on fire, and could maybe have used a little help actually.
I would also like to see a range of different petsummon sets that play differently. Some with more pets, opthers with less pets, some with tougher, more resistant pets, others with dodgier more defensive pets, others with pets that are more geared toward offense. If it's like CoX where the primary set is the one that gives you pet summoning powers and the secondary set is the one you take to heal and buff them (or debuff the mobs they're fighting) then I'd like to see a range of different play styles, like some Masterminds are constantly resummoning their fragile pets while others can rely on their tougher pets to last a lot longer. Sets that have more pets should want less single-target pet buffs to have to apply and more ranged AoE or PBAoE pet buffs. Some masterminds who end up using debuffs on the mobs would need to remain visible because attacking does that (maybe) but others might be able to go ultra-stealthy to survive.
R.S.O. of Phoenix Rising