Reverse Flash is super fast in the comics. His speed is a major factor in his villainous exploits. It's hard to put an exact number on it, but he's definitely up there among the fastest comic characters, making him a formidable opponent for any hero.
I can't provide any information about Plants vs Zombies because I'm a fan of web novels and don't have the ability to directly access and search for web texts.
Well, Eobard Thawne, the Reverse Flash, has an origin deeply tied to his obsession with the Flash. In the 25th century, he idolized the Flash and was determined to have the same powers. Thawne was a very intelligent and somewhat egotistical person. He delved into the science behind Barry Allen's powers and replicated the experiment that created the Flash. But his motives were not pure. Instead of using his new - found speed for good like Barry, he used it for his own self - centered and often malicious goals. His origin story is full of his descent into villainy, all because of his envy and his skewed view of heroism.
The key element is his envy of the Flash. Another is his scientific knowledge which he misuses. And his time - traveling ability which he uses to target Barry Allen.