Well, the fight is on DC earth... But the major player in X-team is our lovely Emma, sinse she's the most cunning one in there when it comes to use of telepathical powers. With other girls (6 of them were Emma's disciples in terms of TP, though there were no great teacher\students friendship betweren them), supporting her...
Team might probably win but like 6\10 and nothing more...but they at least can give Manhunter a real fight. Emma's top 5 Marvel telepath even considering the dampening thing. And she's a most cunning one, if not the most cunning...
Without dampening and with support of others she actually has a chance. Those 70 White Martians feat is quite irrelevant there, since there probably was a "reverse ninja rule"...but it becomes quite irrelevant only when girls aren't stupid enough to try and take him solo, not by acting as a team. One by one, J'onn slaughters them. As a team with the leader- they might last against him and even win.
By the way, is Martian Manhunter allowed to use his shapeshifting powers to boost his TP abilities (like stretching his nervous system thus "turning into the tree" like he has done onse for planetary-scanning feat)? Or is that just an astral plane fight?