Counter Picking.

Bane is a hard counter to Huskar. Not the other way around. With Enfeeble Huskar has high attack speed but deals no damage (which also means no lifesteal). And Fiend's Grip locks him in place which stops his DPS. Anything with a BKB-piercing stun makes Huskar unplayable.
Bane is a disabler not a nuker.

Ok so Meepo. Best counter is Ember Spirit without question (anyone saying Earthshaker needs to go back to math class).
Imba spirit can pretty much two-shot Meepo with double battlefury (one-shot if he's ahead)!. Since each Meepo hit cleaves 70% of the damage to the other ones, it effectively increases the damage by...280%. If Ember has 300 attack damage, one SoF will deal 840 pure damage (that isn't reduced by anything) to every Meepo. And that's just the cleave damage, on top of the regular damage. Rinse and repeat, And then Ember gets a Daedalus...GG boys. Oh and he can escape Earthbind also, since his stupid remnant thingy isn't considered a blink (volvo pls).

Faceless Void for Ember Spirit? Or even anti mage, Spectre??

Naw, Imba Spirit is countered by long silences, so AM and Spectre won't do a thing. Void may well find his Chrono missing due to Remnant jumping. I'd say Riki hard counters Imba - silence from invis, jump on him, Ember dies in 3 hits with no chance to run.

Riki? Well, if we won't take items into account I would say Slardar - he is impossible to kill even in cloud for Riki and if Riki has revealed himself he has little to no chances to escape again.

Riki is hard countered by a Bounty Hunter with a Dust of Appearance.Trace him, he purges, dust him, he purges, track him again.Lol easy way to destroy his purge count.

Bh can't manfight Riki in cloud. How can you see him before he strikes without Sentries(items are not allowed)? Riki has no diffusal, and even if he had Slar could basically do the same with just a little less success.

Slardar>Bh because he doesn't die in the cloud.

For Slardar, someone with disables, chase and hitting power... ... Centaur Warrunner ?

Riki: Hmm, ever try Bounty Hunter with an Orchid Malevolence? That will help against smoke and Blink Strike. And if he is going to purge with Diffusal Blade, he will only one off, either get the Track off or the Soul Burn off. But i haven't seen a Riki with Diffisual Blade in a long time, they only go for Mask of Madness and Skull Basher now since the new meta, so an Bounty Hunter with an Orchid Malevolence will wreck him.

Slardar: High damage output because of ridiculous ultimate, hmm, a long range damage dealer like Drow Ranger or Sniper will tick him off easily. Slardar can crush Drow Ranger and Sniper and vise verca, it depends on who get the first hit on.

for centaur, some one who does not care about magical damage while dealing a lot of damage. Lifestealer

I would pick Phantom Assassin to counter Lifestealer because she deals lots of physical damage.