These answers are taken from the site of one of my biggest influences in mentalism, the world-famous Richard Osterlind, although I changed some answers to suit me personally, which I will note in blue font.
This is the resource to refer to if you want to know exactly what a Mentalist is.
What is a Mentalist?
A mentalist is an individual with the ability to identify and manipulate one or more of the parapsychological elements of the human psyche. I, like Osterlind, have specialized in the areas of ESP (Extra Sensory Perception), Mindreading, Psychokinesis and Suggestion.
Is a Mentalist a magician?
It's difficult to answer that question without raising some very tricky questions. Yes, most mentalists are also magicians. Yes, both mentalists and magicians seem to achieve things that seem to be outside the realms of reality.
But if the definition of a magician is one who "tricks" people through illusion or sleight of hand, then a mentalist is not a magician. When you watch a magician, you know he is fooling you, and the only barometer by which you are entertained is that you, despite knowing full well that you are being fooled, cannot pinpoint how he does it. A magician's implicit promise is a challenge to you: you will not catch him.
A mentalist, in contrast, is someone who "collaborates" with people to achieve their feats. If the person is in the least bit unwilling to aid the mentalist as he attempts to undertake a particular test, then there is a good chance that the mentalist will be unable to achieve what he intends to achieve. A mentalist's implicit promise is a collaboration with you: you will help him achieve the seemingly impossible.
Is a Mentalist psychic?
The term "psychic" has been a bit overused and abused in today's media. It conjures up everything from carnival fortune tellers to the infamous "Psychic Hot Line." I think it is fair to say that everyone has the potential to exercise some level of extrasensory or non-physical power. Much like a sense that can be sharpened to compensate for the loss of another sense or the way human memory can be expanded and sharpened, one's psychic potential is always an unknown until it is revealed and explored. The ability to focus on that potential and to expand its boundaries is at the heart of a psychic's extrasensory power.
Like Derren Brown, I emphasize that my skill in being "psychic" is less about being psychic in common parlance, and more a display of psychology, insight, suggestion, guesswork, misdirection, and showmanship. While I will make no claim of having special gifts that none of us can tap into, I can safely say that I am one of the few people who actively choose to tap into the vast well of the innate potency of the human mind, both as a Philosopher and a Mentalist.
Can you "read my mind?"
I have yet to see anyone outside of Hollywood who is truly able to read someone else's mind. Having said that, I believe - and demonstrate to an audience's delight - that it is quite possible to detect individual thoughts or thought processes, to explore them in context with other indicators or clues (verbal, non-verbal, historical, etc.), and influence what a person will think. This is called suggestion or "Power of Suggestion."
Can an individual prevent you from reading specific thoughts?
The human mind is an amazing thing. Just as there are widely varied levels of intellectual capability, people vary greatly in the degree to which they open themselves up verbally or non-verbally, consciously - or unconsciously. We always hear about how certain people are more susceptible to the power of suggestion. Others are reluctant to open themselves up to the concept of psychic energy and paranormal phenomena. The truth is, without someone who is willing to meet me halfway on stage, the mind retains its secrets like an iron box.
Do you ever use illusion in your show?
I am an entertainer. I love mystery and creating mystery. I always try to give the impression what I do is extraordinary. That involves using illusion in the same way as theatrical productions, movies and television. The goal of my performance is to create an environment that includes humor, awe, and wonder.
Are you ever wrong?
Mentalism is an art that requires a lot of attunement, and to say that I have a hit rate of 100% would be absurd. In spite of that, I would say that over the time since I have gone public, I have been steadily improving my skills to a very reliable rate, as most of the people who have seen me perform would know.
Do you ever teach any of your skills?
As a friend of The Story Circle, a good deal of them are privy to some of my work and my insights, albeit I am not alone in that department insofar as the members of TSC are all very aware of the workings of the mentalist. However, I am a teacher by profession as well, and welcome the opportunity to impart my skills to those willing enough to learn, and have used my skills to aid my attempts at elucidation in seminars and classes that I have been involved in.
What do you wish to accomplish?
As a Philosopher and as an educator, I am after the unlocking of wonder within those whom I do my mentalism for. In a world of cynicism where we seem to know how everything works, it is comforting to know that the very thing that tries to make sense of our world, our minds, is the very thing whose potency we understand the least.
As an entertainer, I desire nothing but the utmost entertainment of my audience. Whether through a humorous performance or a nerve-wracking crescendo, I am willing to pull out all the stops to make my mark as a Filipino mentalist, as an "ambassador" of sorts to the rest of the world in the realm of mentalism.