The easiest would be to have the main target whatever you'd like to be CC'd.
Hit your assist key, so all of your slaves are now assisting the master toon.
Have a macro, keybound so only the slave does anything when you press it.
I haven't used cc's in forever, just blow things up. Pretty sure my cc was something like this:

#show Polymorph
/focus [mod:alt]
/cast [target=focus, nomod] Polymorph

In the case of pets, the easiest would be to have them on Defensive.
So when the hunter/warlock attacks, they also attack.
A safer method - have the pet on passive, and add, "/petattack" to each of your attack macro's.








When I implemented my system, Jamba did not have the auto promote feature.
If I were doing it again, or redesigning my system, I'd consider this.
However, even running with no addons at all, you can switch leaders and target effectively.

Smart Buff is a strong option, as are numerous addons out there.
A lot of the macro's are for illustration purposes.
Several examples show what you can do with this assist method.

The Party1 as assist, aside from two action bars for paging, is essentially as simple as assist the focus.
At the same time, it leaves the Focus free, for CC's or for PvP use.