Those abilities most probably left with Darwin. However in Deadly Genesis it shows that Telepathy will only work on Vulcan when he allows you to access his mind. If he doesn't you just receive psychic backlash like Emma Frost did. (Remember though Emma is a weaker Telepath then X-Man, she attempted to probe Gabriel without him being aware of her and in doing so had her powers backfire on herself, further proving my point)
More evidence, where Gabriel causes mutant powers to backfire on their owners is when Kitty attempts to phase through him. Kitty is immobilized by her own power and Vulcan is unscathed.
Meaning X-Man has no way of attacking him as his Psionic Energy will be shut off, caused to backfire and manipulated by Gabriel.
Both incarnations God-Like Vulcan and Current Vulcan take this.
Make it the most powerful incarnation of both and you have yourself an interesting match.
Current Vulcan vs. Pre Shaman X-Man.
I am going with Vulcan. It cant warp my mind around the reason why. Though it would be a hell of a match, since X-Man and Vulcan suffer from accelerated age, huge ego’s, and big powers to boot.
Problem are:
Vulcan has experience dealing with high grade Psychics. X-Man at this point does not.
Vulcan does not risk of overusing its powers (Omega= no define limit). The more power X-Man taps into, the more he risks a burn out. Though for an Omega, X-Man seems to contain more power (unlimited); while Vulcan seeks outside sources to replenish.
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Shaman X-Man vs. Vulcan Plus.
Shaman X-Man, at this point gained the experience of his alternate self. So you see a bump in maturity, and how he deals with the given situation. It also helps to know that their powers merged, with X-Man receiving the better end of the deal.
Vulcan Plus: Darwin (instant adaptability) , Petra (geo-kenises), and Sway (time manipulation). Respectively, this version seems more competent then when he lost his powers and later became Emperor Vulcan.
Long term battle.
I am going to say of the bat, Vulcan takes a prolong battle. Again X-Man risks burn out, and instant adaptation is a ***** to boot.
Short term battle.
Goes to X-Man. Overall he just strikes me as a more cautious, sturdier character. Look at the opponents, and significant showing each has place. X-Man is off to police the multiverse…Vulcan by sheer luck to over the Shiar Empire.