Okay, i Decided to Come up With this for Many Reasons.
1) not many people play orc =/
2) orc isn't very popular
3) if you get good with orc, you will dominate ladder!
1v1 Strategies and Hero Choices
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Against Human
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Human is a Very Versatile race, which means you need to compete with them at there own game.
Human Usually Goes Arch Mage first and tries for fast tech, to counter this you can go...
Blade Master with Continous Harasses and Rush with your Grunt
OR
if you get farseer, just merely out creep the human
Unit Choices
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Grunts, Tech To Shaman, Spirit Walker, Tauren Raiders...
Why These Units?
SImple, Grunts are Great Starting meat against rifles and footman = Good
Teching to Shaman Provides you with Some Great Hero Trapping Combo's Spamming purge = Good
Spirit Walker.... Human Casters are a bit Agressive yes?? not anymore... = Good
Tauren.... Best Melee in the Game =Good
Raider = If they Human Does Decide to Get Air, Raiders are your best choice = Good
Alternate Choices Against Human May Vary = Post Below if You Don't like This Section.
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Against Night Elf
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Night Elf's Race Mostly Depends on Dryad And Bears... To Counter This,
Expect them to get Demon Hunter or Warden (this is 1v1 afterall)
To Counter this , Do Not Get Blade Master. (unless you map hack and are decent)
i Would Recommend Tauren Chieftain or Far Seer, Why ?
Once Again, Far Seer is a Very Aggressive hero, it allows you to creep faster which in return gives you a great advantage over any anymore, better or worse.
And Tauren Chieftain = Stomping out on there Heroes, Hero Focusing and Owning the Bears? =
WOW
Sometimes if you Kill a Night Elf's Hero to Much They Leave. Trust me, i know.
Unit Choices

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i would recommend getting Head Hunters, to Kodo, Wyvern, Tauren.. or just Grunt, Kodo, Shaman, Tauren
Why?
Headhunters Will Destroy a Night Elf's Huntresses, What Can i Night Elf Do WIth out Those

oh noes!
Kodo's Give to Your Army extra Damage, which is good, night elf race is literally defenseless to mass piercing, unless they have bears or mountain giants, which is fine, eat them. =)
Wyvern would Take out the Dryads from behind while your mellee (taurens) focus there armies.
you could get Grunts kodo Shaman Tauren, That also works, but is a bit weaker to rushes i'd recommend TC if you want that.
Orc Against Undead........(made easy)
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Undead's Race is Pathetic Against Melee, All they Can Do is Get Fiends?
WOW
Trust me, Rarely any Undead's are Smart enough to Get Ghouls against an Orc.
Expecting the obvious, Death Knight, Fiends, Stats, Wyrms, Aboms etc
You Can Judge the Hero Choices, i Would Recommend Tauren Chieftain... and Only Tauren...
(then again you map hack get blade master doesn't matter=/)
Tauren Chieftains Stomp will Crush the Undeads Fiends Stunning them, Your Grunts will Devastate the game that way,
Units?
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Grunts, Raider, Shaman, Tauren, (Optional to get 1 or 2 Kodos)
Why
Since The Undeads Fiends are So Weak to Melee, Stomping and Grunting will Rape, As Soon as you Get Ensnare ?? it's over. Stomp Net Net ! Stomp ! Omg I lost My Heroes?? i gotta leave now bye imba orc !
Tauren are Great melee after your grunt tech, and shamans used for disabling purge or casting lightning shield (on the fiend clump of course !) Unless they Don't get Destroyers then it's okay to mix in the BLOODLUST most orc's are crazy about.
My Favorite !! Orc Vs Orc !
This is a Very Fun Game, What you Need? What Hero Choices?
Most Orc's will Get Blade Master *sigh stupid orcs*
But i'd Recommend TC, Or BladeMaster ( i know i just complained about that )
Most Orcs Get Grunts, hoorah ! mass stomp ! =D!
They Get Far Seers

Blade Master FTW !
Unit Choices
Grunt, Raider, Kodo, Shaman, Spirit Walker, (Tauren?)
Grunts are basic against orc, of course =/
Raiders got that ensnare that you love so much, spam ensnare on heroes, stomp, focus fire, orc's melee is defenseless !
Kodo

Whoever Can Damage More Wins, + You Devour there army

Shaman.... Blood Lust, Of Course? Purge
Spirit Walkers, to Get Rid of Enemies Blood lust !
Tauren... for good melee
Wow? i Just Told you How to Own with Orc in Solo....
+rep if i helped, thanks
feel free to leave questions or comments!