But Aquaman's telepathy is going to be great against Marvel Atlanteans, and Arthur's not all DC Atlantis has going for it. Tempest is a rather powerful mage, and their conventional military was quite large.
Aquaman>>Namor
And then you have Tempest, Mera, Koryak, Dolphin, Atlan, the kings personal guards, and acces to the other cities of Atlantis that include a race of powerful mages, a race of warrior beasts and a floating tech city.
Not to mention their regular army described as the more powerful in the world.