Character description reads:
One of the most powerful enemies we encounter this season, Atom Smasher has come to Central City to kill The Flash. His incredible strength and ability to grow to enormous size makes him more than a match for Flash and the entire S.T.A.R. Labs team will have to come together to find a way to defeat him.
So it seems the Flash is not making many friends come season 2.
At SDCC, producers said that while the particle accelerator explosion that gave rise to metahumans in Season 1 of The Flash had been the main source for introducing powered characters. This time around it would be Earth-2 transforming such characters into metahumans. This by extension could see the return of many characters thought gone in season 1, not to mention new avenues to explore in terms of introducing new DC characters and comic arcs, like JSA and Infinity, Inc.