Counter Commander concept

I have seen people discussing this a lot while suggesting Commanders for their loadouts and i really can't understand how it works. The only example of counter Commander i know is that OKW's fortifications counters USF's Heavy Cavalry. How does that work, how do we know that a specific Commander from a faction counters a specific Commander of another faction? Can you give me some examples and how we reach to that conclusion?

I'd assume it's specific doctrinal abilities that deal with certain strategies. Advanced Emplacements for example has two doctrines (OKW Fortifications and OST Spearhead) that counter it hard.

Not all commanders "counter" another, or have counters. Nor are all counters equally powerful.

OKW Fortifications "counters" Heavy Cavalry because there is no effective answer in the USF arsenal (doctrinal or non-doctrinal) against the 8.8cm Pak 43, which can obliterate the M26 Pershing (the strongest point of the doctrine) on a dime. Static units like the Pak 43 are countered by howitzers or rocket artillery, both of which are not present in the USF stock arsenal nor the Heavy Cavalry Commander.

WM Spearhead doesn't "counter" Brit Advanced Emplacements very hard aside from the Sdkfz. 250/6 Mortar HT and (to some extent) the Fragmentation Bombs. I would argue that Festung Support is a harder counter to Advanced Emplacements and emplacement play in general.

Any commander with a howitzer (the 10.5cm leFH 18) is extremely effective against Brit emplacements, as howitzers deal extra damage to emplacements. Also, the Advanced Emplacements commander has no tools to help it deal with a 10.5cm leFH 18 located on the other side of the map.

The way I understand this is as follows: a "counter commander" is the presence of one or more doctrinal units or abilities that cannot be dealt with easily with both the opponent's stock arsenal and what the opponent's Commander has to offer.

As an example, for WM I run Blitzkrieg, German Mechanized, and Mobile Defense.

Blitzkrieg is my "late-game" commander, where I had a decent early and mid game and would like some tools to help me close out the game. Panzer smoke can keep my vehicles alive, Recon planes help me spot what my opponent has, Command P4 makes all of my units much more durable, and the JU-87G Stuka loiter is very effective against allied armor.

German Mechanized is my "counter commander." WM has few tools to effectively deal with Brit emplacement play, and German Mechanized offers the tools to do so. Grenadier HT can help you deal with Brit infantry away from their emplacements. Smoke bombs are great at blinding 40mm Bofors AAA and 17-prd ATGs. Spotting Scopes are wonderful to know what you're up against (so you don't accidentally run into a 17-prd and get your armor nuked). Command P4 makes all of my units much more durable. 10.5cm leFH 18 dismantles emplacements as if they were sandcastles.

Mobile Defense is my "emergency" commander. If I am behind by 3CPs and/or run up against heavy light vehicle play and am in need of extra Panzerfausts and the Sdkfz. 234/2 Puma, I will choose this commander to save my mid game.