It might have come back with some of the Eternals stories in the past 10-15 years, but he gave up most of his high end eternals powers in favor of speed...now, he did get SO fast at one point, and stuck that way that only the Flash knockoff could interact with him...

Sped up Makkari functions at top end Flash speeds, and with greater strength and durability, but without speed tricks and speed force abilities...the way Flash often fights, he'd be in trouble, but use of speed force would give him the win, or I could see a double KO.

Without his speed up (not sure if its a real powerup), he's fast enough to make the flash work for it, but also getting into strength levels and versatility that makes him a tough fight for Flash...a lot like Zum (as mentioned elsewhere in the thread)....