Not sure if I'm in time to be helpful but....
Can't help you choose the right units, but I got some ideas for your general strategy.
Get some tough CC guys on the Seer council. Doing this will limit their psychic power use.
Keep the orks off the guardians as they will be hard pressed to survive the BS4 shuriken fire.
It may be a little rude but make sure the Ulthwe player declares which guardians are Black guardians. Only compulsory troops count as black guardians. That usually means two units, unless you play some special mission. Had a guy fail to understand this and bought several weapon platforms only to find that two of them were BS4
