Probably these questions were tackled elsewhere in this Forum:
a) Can exorcisms be performed by lay persons? Here I'm not implying the full-blown exorcisms performed by priests, but a simpler one.
b) I recall having read that Pope Pius XII attempted an exorcism on Hitler from a distance. Is this true, and if yes, can similar exorcisms be attempted by lay persons?
A) Not exorcisms per se, but you can say the St. Michael prayer, sprinkle holy water, and stuff like that. Just don't start a company or buy an 800-number. The Catholic Faith is against a Ghostbusters-style group of laymen fighting the devil professionally (for others).
Generally, the "lesser" or "weak" exorcisms a layman can do should also be done only for oneself and one's immediate family, and even then, such weak exorcisms are only a stop-gap measure, if that. One must still have recourse to a priest. Remember that the devil is real, he is very clever and has angelic powers, and a layman should never presume (out of pride, boasting, emotional zeal, etc.) to want to "take him on". You certainly don't want to mess with the devil, any more than you have to. Don't talk to him, etc. as he will use his angelic intellect against you, and he is better than any hypnotist, motivational speaker, salesman, magnetic personality, or "people person". Ever heard of the salesman so convincing he could sell refrigerators to the Eskimos? Well, the devil could do that, so be careful.
In fact, if a man said something like, "Man, I'm gonna kick the devil's @$$" or other similar smack-talk, would prove that the devil already has a measure of influence over him! That is the devil's spirit, the spirit of pride, and not that of God and His saints.
Out of humility (which is the only way to beat the devil), we need to leave the main, front-line, DIRECT fighting of the devil to our priests, who have a special power over him by virtue of their ordination. It is their job to fight the devil with special Exorcisms which are spoken IN THE VOICE OF THE CHURCH which makes them much more powerful.
And a PRIEST doing an exorcism has several advantages:
A) humility
B) he is doing it out of obedience
C) He has the authority and voice of the Church, the bride of Christ
D) He has the priestly character
E) Optional, but he SHOULD be holier, with a stronger prayer life, less attachments to the world, more virtue and less vices, etc.
F) Optional, but he should be availing himself of frequent confession, so the devil will have less to expose/talk about while the priest is fighting him. Remember, the devil knows your sins and will be happy to use them against you.
I would never dream of presuming to do an exorcism myself. Just the act of a layman presuming to exorcise someone WOULD PRECLUDE THE POSSIBILITY OF HUMILITY, since it's not the layman's place. And he certainly isn't being ordered by anyone, much less the Church, to do so. So he can forget the protective cloak of Obedience. No priestly character, no authority, and no ability to speak in the voice of the Church. (Talk about FORGET THAT!)
In short, let the professionals do their work.
B) I never heard of this, but no, you can't do an exorcism
properly called as a layman. See A).