I was not sure how the Ultimates team ability works. What does it mean when it says Members of this team ignore the effects of hindering terrain on movement,(i understand that)
combat, and powers and team abilities.(understand that)

so the ultimates can ignore opponets powers??

also the Ultimate X-men team abilities, if i have 4 different xmen on my team can i give each one a different opposing character? thanks for your help.

Well the Ultimates can ignore the effects of hindering terrain on opponents powers, just as it says. The primary example of this is stealth - The character with stealth simply doesn't have anything to hide behind since no hindering terrain counts for the Ultimates.

And as far as I know, all X-men can target different characters/teams.