Heroes counters

[Gandalf The Gray]

my thoughts were what if some heroes will be able to counter some other heroes

[Walküre]

my thoughts were what if some heroes will be able to counter some other heroes

Very deep thoughts 

The heroes have generally been enhanced a bit, and made more resistant in the Patch 4.1.
Gandalf, for example, regained part of his iconic strength and effect due to his role in the faction and Magic.
The heroes are also more resistant towards creatures and other heroes.
Keep in my mind, though, that, to counter effectively another hero, you should always use wisely the Hero Killers and their powers, which serve their role 

[Gandalf The Gray]

do you know anything about sauron cuz i think he is weak even with his ring

[Walküre]

First of all, we have to consider that Sauron (Necromancer form) has to be 'moderately' weak, because he is regaining his powers, and Mordor has also the Witch-king as its most powerful hero, until Sauron becomes Gorthaur or gets the One Ring.

Sauron (with the One Ring) still has the most powerful powers set among all the heroes of the Edain Mod; but you can't expect him to the 'walking fortress' he used to be in BFME2