Hmm, I cant find any mention of her having a specific role in the Titan war. She's more or less of the same generation as Zeus and the other Olympians, so Id thought of her as one of them rather than a titan (damn it's a fuzzy line) but she wasnt one of the ones that Cronus ate, so mabe not. At the wiki level of research there's apparently a lot of debate about her status: apparently only Hesiod's account describes her in such an ascendant way, in stark contrast to other sources, to the point that people think he was trying to "promote" the status of his village's locally preferred patron goddess.
EDIT: OK, I found at least one mention on wikipedia of her in the titan war. Grain of Salt on it I think, as the context is that it was one of several excuses used to explain her continued presence in the pantheon, and it directly contradicts the more widely accepted bit where Prometheus and his mother Themis were the noted Titans that sides with the Olympians. Looks like I was wrong about Rhea though, she saved Zeus and thus made the war possible, but doesnt look like anyone thinks she took part in the war itself.
Yeah, pretty much. Greek mythology gets really fuzzy on some details. Everybody wanted their local gods to be more important so they swapped around characters and family lines pretty often along the edges of things. After that, there isn't really a "right" answer. Olympian vs Titan is often debatable, especially for the ones that stick around after the war.
Did a little research. I'm going off
this source. It says it's going off Hesiod's Theogony.