Grodd would never work in the movies for reasons stated above. Its too childish.
The Flash rogues, in general, seem to me to only have anything against Flash if you count PIS. Someone like Captain Boomerang shouldn't be able to hit Flash if he's truly that fast. However, here's my thoughts on some potentials, but keep in mind, they'd need some revamping so they don't come across too comedic. I think we can all agree that we don't want a Flash movie to be rated G:
#1. Zoom - This guy's the coolest Flash villain, in my opinion, by far. His ideas are a nice deviant from the norm as well. Inspire the Flash by giving him a villain for motivation.
#2. Weather Wizard - Though a hokey concept, it would allow a more global perspective of things. For a guy like the Flash, you don't want to keep him in a short space to work with. This way, you could get Flash doing things in different continents and such and some classic maneuvers, like countering a tornado.
#3. Captain Cold - Though Weather Wizard would pull off some bigger scale action sequences and such, Captain Cold is a fan favorite and would need some consideration if not just for that fact. You need to please the fans too, not just the general audience. Without those fans, you wouldn't be in this situation.
#4. Trickster - Obviously wouldn't be the grandest, most diabolical evil villain in history that is threatening the world, but he could definitely be in a film as a minor villain for some comedic relief at his insanity.
Also, a different setup is possible if you're given a trilogy to work with. The first could have someone broad and general like Weather Wizard while dealing with the introduction of the whole concept of the Flash. Second could deal with his ego getting out of control and his lighthearted attitude maximizing, so Zoom tries to motivate him into "becoming a hero again" so to speak. Third, you could go all-out and have Captain Cold lead a bunch of the rogues (Mirror Master, Trickster, Captain Boomerang) into something similar to the JLU episode where they all team up to just rid the city of the Flash.
Now, I'm definitely not claiming to be the biggest Flash fan here, but I know personally I wouldn't want to see the wrong things overplayed. Wally is definitely a more comedic and lighthearted superhero than a lot of those out there, but that doesn't mean this should be a strict comedy. When it becomes a comedy, it becomes cheesy and something that isn't as respected, and if you make a Flash film wanting to please the overall audience that simply thinks of him as "the funny looking guy in red spandex that runs real fast and fights a talking monkey and a guy with a winter coat"...well, say hello to the new Elektra.