Gilda is the character in MLP who satisfies this characterization. She plays it about as straight as it is possible to play, but due to the depth of the archetype she inherently has complexity.
Evil or Hostile
Gilda falls cleanly in the hostile category; she is intentionally rude to brush people off, takes advantage of others to satisfy her needs, and bullies others for no clear reason, other than to keep up appearances of being a bully. Her consistent use of negative adjectives also furthers this idea, appearing to use them, almost on reflex. Her hair and animation style are also very aggressive. Regardless of her malicious intentions, she clearly does not indulge in them all the time, particularly around Rainbow Dash, lending credence to the idea that she is not evil. Later on with backstory such thoughts are confirmed.
Gilda is designed to fulfill the bully archetype. She is more personal, less friendly, competent, and secure than a rival. She is designed to represent a real world personal antagonist, as opposed to the magical, fantastic villain that NMM is. Her character in its first appearance is designed to invoke disgust, as Gilda takes advantage of the freely given kindness of the group, and meets all attempts at intimacy with rejection. She ends up being driven out for being hostile to everyone around her.
Redeemable or Unredeemable
As per word of God, Gilda is redeemable; however unlike NMM her actions still hold relevance. Where everything NMM has done was washed away with her destruction, Gilda still has to come to terms with who she was, rather than just pushing away the bully and hiding it. This leads to a very complex moral dilemma, what must Gilda do to be redeemed? There is no clear answer, as “one good deed is not enough to redeem a man of a life time of wickedness.” If one is not enough, is 1000, 10000? Good deeds are not tokens that can be redeemed at a vending machine, yet they clearly have value. This is the fundamental problem that Gilda faces, how much good is enough? Will it ever be enough? What we have seen in S5 was just one giant step in the right direction, but the road is very long. Will Gilda keep walking it? Or will she return back into her old ways? What about those who will not forgive her. No matter how much white is added to black paint, the paint will always be grey. Saying she is redeemed is a gross simplification of her present position, as redeemed implies her past has been dealt with but for Gilda such is not the case, as it will always be there.
As a personal type antagonist, the bully can draw some of the most varied and strong emotional responses from the audience. Some dismiss her as trash, best taken out and left in the street. Others view her as a woobie, trying to hide her insecurity and fear behind a spiny coat of anger. Some see her as a victim who needs help, love and understanding. Some see her as lost, unsure how to act in such a society. Some see her as an aggressor, causing harm to vindicate her own self-worth, where otherwise she has none. Some view her as trash, and yet are still feel obligated to break her down and fix her, as that might be the right thing to do. Since she is a personal antagonist, she shows the reflections of real life people the audience knows. Those relationships set the standard, through which the audience views Gilda, and can inspire many strong emotions, whether anger, pity, fear, disgust, worry, or sadness. Gilda is a powerful character, not due to her own strengths but due to the hold she has on the audience. She also has many paths to tread, which lead many different ways. As of the end of S5 she is at a crossroads of sorts, she has tasted both flavors, which one will she choose in the long run?
Gilda is a simple portrayal of a complex archetype. One big thing I will like to point out is that she is not indicated to only be one face of the archetype; such interpretation is left to the viewer. Whether she is a monster or merely misunderstood has not been determined, this makes her a very beautiful character. She is what the audience needs her to be, so that they can find conviction in their own lives. Though they likely will bump heads with others who think she is something different.
I am going to hold out on pushing more of these out as I do not see the point of making more if they are not read.