That would break down as Charles, Jean, Emma, then Psylocke.

But it is true that if you dropped the 4 together into a room to fight, the “weakest” telepath here kicks everyone else’s asses. Betsy is immune to telepathy, her telekinesis at least matches Jean’s, and she is a much better fighter than the other 3. Unless the Phoenix Force intervenes or Emma decides to stalemate by becoming diamond, Psylocke would win a rumble if held right now.

Interesting!

I think this is a VERY interesting topic! Marvel’s writers have homogenized their telepaths to the point where they largely all have similar abilities. Or at least POTENTIALLY similar abilities.

For the sake of argument (and if you look at some of the “official” information online, they often read identically, despite some of these characters having never used their powers in the ways listed) let us say that there are certain STANDARDS for most telepaths.

A telepath should, of course, at least be able to receive (and/or send) impressions and thoughts. A high-level telepath should be able to do both, over vast distances, and with multiple targets.

They can often use their telepathy to locate a particular mind, either in a crowd or over great distances. A high-level telepath may be able to scan an entire planet from across the galaxy!

A telepath may also be able to warp, cloud, confuse or otherwise manipulate another person’s perceptions. A high-level telepath may be able to do all of these, again over great distances and possibly to multiple minds.

A telepath often has the ability to influence another’s behavior or perform bits of mind control. A high-level telepath might be able to completely subvert another’s will to their own. And again with the distance and multiple minds.

Lastly, for strictly ‘telepathic’ standards, they can often unleash psionic blasts of pure mental energy to stun the minds of their foes. This can range from sudden shock or pain, to rendering a foe unconscious, to creating mind-death or killing a foe– depending on the power level of the telepath, and the effort used.

Marvel also tends to associate astral projection and mind-shields with telepathy, but I say they are their own powers and, just because many telepaths also have these abilities, does not mean they ALL do. So I will ignore these as “standards” of telepathy.

And so, since Marvel often treats one telepath as having the same set of “standard” powers as any other telepath, the differences then become more important! I think there are several ways to address their differences: 1) each character’s personal outlook and the way they prefer to USE their abilities as dictated by their respective personalities (which are VERY different). 2) each character’s unique powers, however insignificant. 3) the argument of raw power versus training and expertise.

I think these are the biggest three factors in helping differentiate the abilities of these four (and other) psychic characters. I will now adress each of the 3 points for each character listed…

JEAN GREY:
1) Jean has used all of the standard telepathic abilities at one time or another. But she is loath to use mind-control unless she feels she has no other option. She is also less casual about using her telepathy in general, especially on friends or allies.
2) In addition to all the standard telepathic abilites, Jean can also project her astral self and possesses powerful telekinetic abilities. In addition to these already formidable powers, Jean also (sometimes) plays host to the Phoenix Force, which boosts her telepathic and telekinetic powers to unearthly levels and sometimes grants her other vast cosmic powers. All four of these characters have good mental defenses, but I think Jean (despite all her raw power) has the “weakest” mind of the four. She just seems to be overcome by mental energies the most– often when SHE herself initiates the telepathic contact!
3) Power versus training/expertise: I place Jean EASILY at the top of the heap (among these four) in terms of raw power. The other three don’t even come close! As for other comparably-powerful Marvel telepaths, I would say Rachel (currently, 2009) is more powerful. And the Shadow King and Moondragon (WITH the Mind Gem) are about the same power level. As for expertise with her abilities, its very, very close amongst all four. I would place Jean just slightly after Charles and Emma, but a bit ahead of Betsy.

PSYLOCKE:
1) She too has demonstrated the ability to use all the standard telepathic powers. She is probably the least likely of the four to go straight to her telepathy though. Even when she was ‘just’ a telepath, she often waited for the right moment, assessing the situation or trying to worm her way into an enemy’s mind before striking, or simply hesitating. Since becoming a ninja, she usually goes for the physical attack first.
2) Psylocke sometimes (more often in the past) manifests a visual psionic butterfly effect when she uses her telepathic abilities. Neither Betsy nor Jean seem to possess quite the level of talent that Xavier or Frost has with mind-scanning across great distances, even when using Cerebro. Psylocke possesses a psionic knife (formerly)/psychic katana (currently) that is unique to her amongst the four. The knife was able to temporarily disrupt her victim’s neural synapses. The katana can cut thru any non-living material and can also disrupt the way the knife did, but it does not cut living flesh. When Betsy gave up her telepathy to imprison The Shadow King within her mind, Jean Grey helped her awaken her secondary mutation: Betsy’s latent telekinetic talent. The writers have claimed Psylocke has “vast” telekinetic abilities powerful enough to devastate mountain ranges. This seems a bit far-fetched and, thus far, she has not used it to perform anything that impressive. Betsy mostly uses her TK to boost her physical stength, speed, and reflexes in hand to hand combat. She is talented at astral combat and has tremendous mental armor. Lastly (whew!), Psylocke is the only one of the four to possess precognitive abilities—-at least on any recurring basis. The Phoenix Force has given Jean visions and warned her of danger, but that has not proven consistent or repeated itself. Even though she rarely sees use of this power, Psylocke does occasionally receive a precognitive flash or dream.
3) Only recently has Psylocke’s telepathy come back to her. And it seems greatly diminished compared to her power levels before she trapped The Shadow King. But, even at her most powerful, she was still the “weakest” of the four here, in terms of overall telepathic might. She also comes in last in terms of training & telepathic expertise IMO. But I do give her props for making creative use of her abilities in their currently diminished state!
Psylocke MORE than makes up for any telepathic deficiency (compared to the other 3 Master Telepaths) with a whole host of other powers and abilities none of them have!

PROFESSOR XAVIER:
1) Although Chuck has repeatedly CLAIMED he is hesitant to use his telepathic abilities on someone without permission, or psychically pry into another’s secrets, he is really just blowing smoke! I got like DOZENS of instances that call him on his BS. At least Emma makes no such pretensions about her willingness to invade your mind. He has both the ability AND the willingness to use any or all of the standard telepathic powers.
2) IMO, Charles has no weak areas regarding the standard telepathic abilities. I think he and Emma both possess superior thought-probing and mind-scanning to either Jean or Betsy. He is an expert in astral projection and combat and possesses very strong mental defenses. Xavier does have ONE ability the women here do not have– he has an innate ability to psionically detect mutants. It’s this power that inspired the design for Cerebro!
3) Once the world’s “most powerful telepath” but not anymore! While I say Rachel, Jean, Farouk, and a couple others have more RAW telepathic might, he is still ONE OF the most powerful on the planet. I will go ahead and give him “most SKILLED telepath” though. But I do think he and Emma are virtually equal in expertise. Farouk, Jean, and Betsy are all highly skilled telepaths, but they are not quite in the same arena as Charles and Emma. Charles is able to routinely defeat much more powerful telepaths, like The Shadow King, by outmaneuvering them.

EMMA FROST:
1) Lets face it. Frost has absolutely NO QUALMS about using ANY of her powers at any time on anyone! She would mind-blast her own mother. And she casually seizes control of minds the way someone else might change channels on TV. In fact, unless she is probing for information, her most likely tactic is to go straight to the mind control. Or do both: dominate your will WHILE probing your mind!
2) As far as psychic abilities, I know of none that Emma has that the other 3 don’t also have. Of the four, she easily has the most potent mind-control abilities (probably from exercising this talent so often). She can project astrally and has formidable mental defenses. Her unique ability lies in her secondary mutation: a purely physical ability, her diamond-body form! In this form, she is all but impervious to physical injury, has heightened strength, and is totally immune to all forms of mental attack. The drawback is she cannot access the use of any of her own telepathic abilities while she maintains her diamond form.
3) I place Emma third, just after Xavier (but well ahead of Psylocke) in terms of raw telepathic power. As for telepathic training and expertise, no one beats Chuck. BUT if anyone could challenge that crown, it is she. Frost is able to routinely defeat much more powerful telepaths, like Rachel Grey, by outsmarting them. I say Xavier is only MARGINALLY better than her, and on any given day, in psionic combat, Charles is much more likely to out-power her than psionically outsmart her.

Well that is my assessment of their abilities, how they stack up agaisnt one another, and how I see that they differ. Any thought on my conclusions?

It would be interesting to rank and place some of Marvel’s other telepaths as well: Cable, Moondragon, Elias Bogan, Doctor Druid, Cassandra Nova, Monet St.Croix, Rachel Grey, etc…