The Ares can avoid its sleep attack by using an art once Telethia starts to flap its wings...it cancels the sleep effect and thus Telethia won't follow up with its physical attack. I prefer, however, to use a Lailah Queen to out-tank it by staying in Overdrive constantly, as you get Increased Defense, Immunity to Status Effects, and HP Regen, making it difficult for Telethia to hurt you.