The most common attack I have read about: "You're not a 'real' man/woman".
Meant to indicate that transgender persons are just playing dress-up and cannot compare to cis folks. I haven't experienced this in person yet but see it online a lot. I also think it's interesting that the attacker can just as easily be either gender.
The statement doesn't make a lot of sense unless they define exactly what a "real" person is. Without that I can jump to any number of conclusions, which are probably all wrong. Most of my examples are going to be for trans women but apply just as much to trans men.
Are they saying that only "real" women have a vagina/penis?
That only "real" women can give birth?
Only "real" women have XX chromosomes?
Only "real" women are attractive?
Maybe what they mean is that you didn't get to experience growing up as a cis person did and you cannot understand the experiences.
Vagina/penis. There is surgery for that. Doesn't that satisfy the requirements then? The idea that they are reducing people down to a sex object is already terrible and should be an indication of how they are not seeing women/men for the people they are.
Giving birth. Not every woman can have children. Does that mean they are "less" of a woman? Again reducing people down to reproduction functions isn't a good thing.
Chromosomes. This one would take up an entire article on it's own. This totally disregards people with unusual chromosome patterns (eg. Klinefelter Syndrome). Your DNA is a template. It cannot change (in this way) but it doesn't define your identity. You might as well believe that everyone is born good/evil and fate exists if you think DNA controls you.
Attractiveness. This one doesn't even make sense. It's entirely subjective. There are so many things that one person could find attractive that another would be put off by that it's almost guaranteed someone will find you attractive and someone will not. There are many more cis people in the world and it stands to reason that they are not all attractive.
Experience. It seems so silly to even think about. If I had grown up as the gender I wanted then I wouldn't be trans! Just because I didn't get to experience the beginning of my life as the correct gender doesn't mean that I cannot experience the rest of my life that way. Even with a little thought it makes no logical sense and breaks down quickly. Every person experienced something different. Would this attack be used on a woman from Iraq because she didn't have the same experience in life as the girl from California?
You grew up as a man, therefore you had privileges that girls didn't have! This is a silly argument too. As I understand it this means that nobody can change position in life. In the case of trans women I think this has a fairly obvious hidden meaning. "Nobody would want to lower themselves to the position of a woman!" This attack isn't just used for trans issues. It could be about economics, race, or sexuality. Always implying that one side is "better" than the other. The idea that I was born into something and that it's my fault isn't even a good one. It is a scapegoat to use to never try to be a better person or improve yourself. The people who use this argument are dismissing the idea of empathy. Just because I didn't experience something first-hand doesn't mean I can't understand it. If I see someone burn their hand on the stove I don't assume the stove is cold because I didn't feel it myself.
This is just an argument used to feel superior. It sounds reasonable if you don't think about it at all but it really isn't. Every person's experiences are real to them. There is no one true way to live life.
In the end it sounds a lot like No True Scotsmen.