Majestic angel is one of the milder large angels. However, it will be ok with powder blue or other similar acanthurus. I have a majestic angel with a powder blue and no one ever bothers each other.
that being said, even though majestic angel is shy, it's is by no means weak. mine would defend its territory and kick out the fish that try to enter it, unless the other fish is much bigger and tougher. One time my golden puffer wanted to camp in the majestic's cave, and the majestic let him do that for a day until he left by himself.
always introduce majestic first, regardless of size, before other "large" fish like PBT.