@Evil Emperor Proteus  
Discord would fit more as someone who perpetuates Sloth than someone who commits it, imo. He drove the Mane Six against their elements so that they’d be ineffective against him and drove everything else to chaos afterward, so nopony was doing what they were supposed to be doing.  
And as “To where and Back Again” revealed, Chrysalis was VERY evil.

@Kerion  
HA! Perfect Evillious reference!

@Background Pony #B871  
Her English voice actress is married to Roy’s though, so it’s technically accurate.

@Evil Emperor Proteus
 
On the other hand, imprisoning a princess on their wedding day and impersonating them to drain their groom’s love for them dry, while also attempting to conquer a city and expressing sadistic glee at watching ponies suffer, IS pretty evil.

@Data Expunged  
Sloth isn’t entirely about how physically mobile you are. Unlike Discord, Chrysallis and Sombra actively took an interest in their people and the running of their kingdoms.(for good or ill). Chrysallis arguably isn’t even evil. Wanting to feed and survive is not an evil act.

@Evil Emperor Proteus  
Yeah that makes sense. But he is, in my opinion, one of the more mobile villains in the show. Chrysalis stood around and did nothing but she represents Lust and King Sombra did next to nothing and hes Wrath. I think that Sombra would be more fitting to represent Sloth and Discord would be Wrath. All the other ones, in my honest opinion, are fine the way they are.

@Data Expunged  
I don’t even watch the show and I’d say he represents I perfectly. Dude was just sitting on his throne not worrying about work of tending to his subjects needs, only his own, and just sat around causing chaos. He was defeated twice while sitting down.

I’m rot really sure if Discord would represent Sloth…

@Kerion  
YES!

@ShootingStarAJM  
There are only 7 Sins in modern depictions of the Deadly Sins. Before there were more, though, like Despond, etc…

You forgot Sunset Shimmer and Midnight Sparkle

@Chrysalislover  
Nah, Discord spends most of his time sitting down, letting whatever Chaos he’s brought unfold or playing around rather than working.
 
As for Tirek and Adagio, I see some people seeing the two as very similar or identical in goals. This is not the case, as there is a difference between Greed and Gluttony. In the case of these two characters, Adagio wanted everything to revolve around her and desired control over others and their world, Tirek simply wanted everything everyone else had for himself, not even willing to share it with his cohort - Discord.
 
Starlight represents Pride quite well because she refuses to accept any way but her own, and is even willing to force her viewpoint on others, regardless of how flawed it is, and is even refusing to admit these flaws exist, topped off by the arrogant notion that she is exempt from her own rules and laws. Any society she would create with her regime would be one of ignorance and stagnation.
 
Nightmare Moon and Sombra speak for themselves in actions, really.

@Dead0k  

 
Nah.

@Kerion  
Also the booklet of Ministry’s “From Beer To Eternity” is mostly a Seven Deadly Sins reference.

@Jarkes  
Try looking up any of the fallowing on Youtube and you’ll get my reference. Madness of Duke Venomania, Evil Food Eater Conchita, Daughter of Evil, Tailor Shop on the Enbizaka, Gift from the Princess Who Brought Sleep, Judgement of Corruption, or The Muzzle of Nemesis.
 
As for not going the FMA route, frankly it’s been done to death and there are other series that have the Seven Deadly Sins.

Pride should be Discord, and I’m not sure what Starlight then would have, but the rest are pretty well done :)

@Marnssj  

 
Story of my soul lol

Discord as Sloth is brilliant, because Sloth was originally Despair which was originally defined as doing the wrong thing when you know it’s wrong but care.

Sunset Shimmer not even? OK.

@Background Pony #6438  
My memory’s a bit glitched.
 
Then, she paralyzed Havoc for life.

gluttony greed and envy are all words for want havin’ somethin’

@Roy-of-Asturia  
Lust dated Jean Havoc, not Mustang.

@Kerion
 
I have no idea what you’re referencing, but kudos for not going the obvious route and referencing Fullmetal Alchemist.

So Nightmare Moon is a tailor.  
Discord gives people ‘gifts’.  
Chrysalis lures women to her castle.  
Sombra is somehow related to Adagio.  
Tirek is a cannibal.  
Adagio is a corrupt judge.  
And Starlight is a jilted princess.  
(Cookie to whoever gets the references)

@Jarkes  
Gluttony is mainly consuming more than you need, though there is a list of other ways that count that range from only eating one thing to eating too little, if you can believe that.
 
And greed implies more hoarding than actually using anything you take.