Best 5 man teams

Not much catch :P

Not a lot of stuns too :(

Ideal Five Man (IMO)

1: Ember Spirit ( Safe )
2: Puck ( Mid )
3: Phoenix ( Offlane )
4. Abbadon ( Safe )
5. Witch Doctor ( Safe )

Puck sets up with ult, ES can sleight of fist, Phoenix and WD POP ult, abbadon protects everyone. Some decent stuns, great damage, pretty good pushing power, and lots of heals. Careful for enemy BKBs but you still have right click output with Abba and ES

Maybe put position 3 Doom to counter the core hero with BKB

Magnus + Ursa or any melee core hero should be a pretty fun one
Skywrath + any stun is a good combo
Phantom Lancer + KOTL is pretty good, should be hard to deal with. Make sure KOTL doesn't steal all the farm during and after the laning stage
KOTL + any nuke spammer like Zeus is good
Lich + Axe or Bristleback is a good combo
Dark Seer is good with any team tbh, just need to be played well
Tiny + Ogre Magi is a good combo

knowing comboes is good but you should familiarize yourself with counters too

like nyx > silencer + OD is a pretty obvious one but it leaves the laning stage to be much weaker pre-level 6

there are pro and cons of every combo or counters

There are also some relatively complex ones that depend on very interesting interactions that most people are not prepared for that you can use like Void-Phoenix (with 6.86, your position 1 will probs be in the midlane anyway, unless you run the greedy Phoenix support), AA-Venomancer, and the simple yet beautiful Puck-Gyrocopter.

Glhf! :)

i think treant protector + lich are very good combo for team fighting
spirit breaker + lifestealer the ultimate gank
legion commander + skywrath mage for easy duels
Husker + dazzle OP combo

also consider the global team (blood seeker+Zeus+natures prophet+ancient apparition+spectre)
a pretty balanced team with a high damage and a GLOBAL AOE effects :)

Hope you find it useful gl hf

Even pocket strats like tiny-io, magnus-ember, drow-wr-visage, should be useful.

I don't play ranked at all, but I know you can do some classic stuff like:

Minus armor strat = pick supports like Dazzle and Vengeful Spirit, cores like Slardar, Shadow Fiend, Alchemist, Bristleback, and then someone who profits from this (like a Windranger or a Templar Assassin).

Pushing strat = the other day I went against the following heroes: Lycan, Nature's Prophet and Broodmother. I almost uninstalled, but we managed to win with a all-in fight, because otherwise we would lose, they even had barracks (see here: http://www.dotabuff.com/matches/1966302882) Also consider Shadow Shaman, Razor, Pugna, Jaquiro, Undying and Tiny in this regard.

Another nice idea is to combine big set up ulties (like Ravage, Black Hole or Reverse Polarity with AoE damage like Death Ward, Freezing Field, Sonic Wave, Epicenter, Ghost Ship or Chain Frost.

Just some ideas on top of my head which I hope help you :)

Good luck!