Sorry for the necro, relatively new to the game and wanted to give my thoughts from that perspective and Mind Control was the first power set I went with.
I agree with biostem that telepathy and telekinesis should be removed and given their own set since Mind Control, the way most of the powerset works, is the control over others' minds and having also the control of your mind over matter (telekinesis) in it would be like having fiery aura and fiery melee as the same powerset.
Skills that could be found in a telekinesis powerset : "Force" pushback as an AOE knockback, hurling objects at enemies with the power of your mind, increasing the gravity/body weight of the target to make them slow down, paralysis of one target (lower version of telekinesis), Mind Barrier (self resistance to psi effects) or a Protective Bubble like Force Field Generator, Contortion (attacking a target making them go into knockdown ragdoll mode from the attack), to name some ideas. Such a powerset could be a secondary powerset for Mind Control and vice versa.
As for the replacement in the Mind Control category, definitely a pet would be welcome. What is the point of Mind Control if you can't enslave people with (villain speaking) or convert/ redeem/ reform them (hero speaking)? There should be a skill called "Brainwashing" or "Servitude" or "Conversion" which would "petify" a target by resurrecting a defeated enemy as your servant if the target is the same level or lower than your character (though maybe with enhancements like accuracy, that level requirement could increase every 50% or so depending on balance). The lore being that you've incapacitated them and now their mind is fully open to your suggestions without offering any resistance (would not work on machines).
Very often it was frustrating to have a target confused just standing there because there was no other enemy visible from their point of view even though I could see other enemies in the back and there was no way to tell the confused mob to come with me. Brainwashing would solve that issue and be fun to play, going on a "shopping spree" to see who would make a nice servant to have around until they get killed (could potentially affect pve villains and heroes too if they meet the level criteria, usually those you meet in bank robberies). Would be funny if used in pvp, it would create a clone of the defeated player as your pet but that could be difficult to implement.
In the power customization, you could select their emote stance when resting (atease, militarysalute, salute, praising, kneel, defeated, akimbo, crossarm, sleep, wounded)
"Brainwash" / "Servitude" / "Conversion" would allow you to only have one servant at a time but controllable like Masterminds (ideally it would be great if they would not attack confused mobs) but a stronger version could be "Wider Influence" to replace the second missing power, could let you have two.
Description of the power would be: "Brainwash" / "Servitude" / "Conversion" : You take over the mind of a fallen enemy the same as or lower level than you and make them see things your way. You resurrect the target with full hit points and endurance. The resurrected target is now loyal to you and will do your bidding as you see fit. They would even be willing to die for you.
"Wider Influence" : You can take control of the minds of up to two fallen enemies at a time resurrecting them with full hit points and endurance. The targets must be the same level as you or lower. The resurrected targets will follow your every command until death do you part.
Either that or have a Mastermind typical power as a selectable secondary powerset for mind controllers as it would fit theme wise like Thugs.
For other suggestions, maybe Mesmerize could have an additional effect similar to vomiting from Noxious Gas. In this case, it would have 1% chance of triggering the emote Chicken to make them behave like one and increase the time of sleep starting after the extra duration of the emote (same for Mass Hypnosis).