Not many. It's important to remember that teams are groups of individuals. Considering teams 'enemies' is easy to fall into, but it's also usually wrong. Things are more complicated than that; I've had friends whose teammates hate me, and I'm sure a lot of people have similar experiences.
That said, there are one or two teams who seem to have trouble with that reasoning, and dislike us pretty strongly. I'd avoid Hydra in particular, and, though they're not as universally prone to it, Vulpecula.
*globes of color flick into existence in front of you; light green when he mentions Hydra, and orange when he mentions Vulpecula*
There are good and friendly people on both teams, but they've probably been warned against anyone wearing our color, and there are others who...aren't as friendly. So be careful if you approach them.