Can anyone provide a list of monsters that will usually lead other groups of monsters and monsters that will follow them.

hobgoblins will usually lead goblins and bugbears maybe even an ogre.

You could have a dire wolf leading a pack of wolves.

Perhaps a young dragon or dragon wyrmling could lead a band of kobolds.

Any more powerful fiend will command weaker ones. 

Again with humanoids, a more powerful one will probably lead weaker ones. A noble may also command a few knights. 

Wights, Wraiths, lichs and vampires could command all manner of undead and maybe a few living enemies. 

I hope this helps. 

Is there a specific sort of encounter you had in mind? That would help narrow this down a bit. 

For the most part, you can justify a lot of "leader/follower" combinations of monsters.

The Mindflayer statblock explicitly states that they use their psychic powers to directly control Troglodytes, Grimlocks, Quaggoths, and Ogres, but those are more just examples of the types of creatures they can control... any low INT creature can easily be dominated and controlled by a Mindflayer, so that opens up a lot of the Monster Manual as minions. They also have their Intellect Devourers, which is good if you want to throw a deadly threat at the party that's only CR2... and can also be used to justify having agents of other races, since an Intellect Devourer can take over the bodies of Humanoids by literally replacing their brains. Mindflayers themselves are also subservient to an Elder Brain, so it's basically a Pyramid Scheme of minions working for other minions to feed a big ol' brain in a jar.

Materiel plane encounters but other then that I'm just looking for combination ideas.

Any particular level range, or are you just looking for dynamic encounters that seem cool and interesting?

around 5th level

Some brief ideas:

1. 1 Blue Dragon Wyrmling and its 8 Kobold minions (Medium strength encounter). Maybe they live in an abandoned mine of some kind.
2. 1 Brain in a Jar, 5 Gnoll Witherlings, and a Bone Whelk (Medium Encounter). The brain is a former gnoll that is trapped in the jar mentally hungering for all time with no respite. The witherlings are the remains of its former pack. It rides around on the Bone Whelk like a slimy snail sled. The brain's jar protects it from the Bone Whelk's death scream.
3. 1 Chuul and 3 Derro (Medium Encounter). The Derro trio found the Chuul in the Underdark and have trained it as their muscle. They send it out some nights to raid the local farms and either loot or enslave whatever it brings back.
4. 1 Cambion, 1 Imp, and 3 Cultists (Hard Encounter). The cultists summoned the devil, however, they lost control and not he is the boss. He has called forth his Imp minion from the nine hells as well to assist in his plans.
5. 1 Fire Elemental and 4 Steam Mephits (Hard Encounter). By chance or accident, a portal to the elemental plane of fire has opened up under a nearby lake that used to be a flooded quarry mine. As the water boils away to steam, a dungeon of sorts appears filled with strange elemental imp-like creatures commanded by a Fire Elemental that is angry that it is trapped on this side of the portal.