This is….kinda the point. Every villain here, in some way, temporarily, defeated the Mane Six.

@Background Pony #5256  
Of course they did. I’m just saying that Cozy has reason to want revenge on the Mane 6 too.

@PurpleWonderPower  
You make it sound like Spike’s a fraud. Hmm… interesting episode idea. Perhaps we can see that explored!
 
And the Mane 6 wouldn’ve captured Cozy if the Student 6 didn’t save the magic, so c’mon, that finale belonged to the Student 6 no doubt! ;)

Twilight was the one who found the Crystal Heart in the first place, and the one who exposed Chrysalis as a fraud at the Royal Canterlot Wedding. Also, the Young Six may have foiled Cozy’s plot, but the Mane 6 are the ones who captured her, exposed her and got her locked in Tartarus.

Yeah but Twilight is the head of the proverbial snake that he intends to cut off.

Lol  
That is true

@Background Pony #4FD3  
Okay yeah that makes sense.

@Fwelin  
Alright so they were “Twilight” - that’s not the entire Mane 6 tho

@Derpyfan  
Spike’s friendship with Twilight and her trust in him and willingness to save the Empire over passing her test

They weren’t the sole reasons for their defeats, but they (or at least Twilight) played large roles in all but Cozy.
 
Twilight figured out that something was wrong with Cadance, then freed the real Cadance, who beat Chrysalis the first time (along with Shining).
 
Twilight did most of the work finding and retrieving the Crystal Heart, and the other mane six kept the Crystal Ponies’ spirits up so they could supercharge it at the end. Spike and Cadance were big players, but the mane six were important too.
 
Cozy was the only one they didn’t help against, but then, no-one did; she successfully trapped the student six in her magic construct, but then the Tree of Harmony itself saved them and basically beat Cozy itself.

@Background Pony #4FD3  
Spike’s friendship with Twilight and her trust in him and willingness to save the Empire over passing her test

If you want to get technical, The Mane 6 aren’t Superheroes, That’s the Humane 7.
 
The Mane 6’s Rouge gallery is not that large, heck the list of recurring antagonist for a long time consisted of Diamond Tiara.
 
Then Reformed Villains Trixie, Discord, Starlight, and Thorax.
 
We got the Flim Flam Brothers and Iron Will as non-villains.
 
There’s just not a lot of Villains, it’s more slice of life.
 
Also callin it now, there going to be a Reformation at the end.

@Background Pony #4FD3  
I don’t see how that applies to King Sombra.

Every defeat was still ostensibly at the hooves of the mane six, considering those victories were built on the foundations of their teachings.

@TheKman100  
Exactly! Now that Sombra’s not around, no one’s gonna mention Spike!

Sure… but now the two who are still alive can think of the outliers.