[raven925]

I have heard many times that putting you best unit wether it be in CC or Shooting against you opponents best unit is not the best idea, and that your best unit should focus on the weaker units?

 

[KingOfCheese]

How long is a piece of string?

It depends on so many variables.

 

[Supersonic Banana]

It depends on what you mean as as your best unit could be some tooled up terminators but they'd get busted up by a large mob of ork boys- one of your opponants weakest units. So I don't think that you can have 'best' units as the enemy will almost always have ways to take them down.
However, I think I know what you mean and yes you don't pit your best against their best (unless you have a pre-planned duel organised) as even if you win they will come out battered and easiliy dealt with.
As an example, you are running Abaddon. He runs into the Nightbringer. Exactly.

 

[KingOfCheese]

Ork Boyz a weak unit?

They are one of the best units in the Codex. In fact, they are one of the best units in all of 40k.

But yes, a lot of things in the game are very rock-paper-scissors. The idea of the game is to try and use your rock against their scissors, your scissors against their paper, and your paper against their rock.

 

[Supersonic Banana]

Ork Boyz a weak unit?

They are one of the best units in the Codex. In fact, they are one of the best units in all of 40k.

Yes ork boyz are a weak unit but even that depends on size and circumstance. For instance a unit of ten isn't going to do anything but a unit of thirty can shread terminators and tanks. However, if they don't get the charge then they're quite easy to kill (speaking from experiance).