Is there a plugin with specific C++ motions? Like
vif - visual inside function.
That could be very useful for some macros etc.
Regarding the precise vif, I did post link + explanation on how to achieve this correctly (this is unfortunately not a trivial task) from vim on vi.SE.
Regarding the other possible motions, well there are general plugins to select parameters (I have this within lh-cpp, and I'm aware of one another solution at least), there are other plugins that help to select words within camelCase or snake_case identifiers, but they are not C++ specific.
What else are you specifically looking for?