Those are not aggressors, they are Su30MKK strikers and would likely employ low altitude high speed penetration tactics in combat.
The pinkish red colour they have been painted in is actually a very good approximation of the soil colour of large ares of Southern China when viewed from the air.
If the PLAAF wanted to paint their aggressors distinctively different from line aircraft, they would likely have opted for a more western style paint scheme to better simulate the looks of potential adversaries. What more, the PLAAF would not have used aging MKKs as aggressors. The MKK has had significant beefing up of the airframe to carry heavier ATG loads, and as much lost a measure of agility. The airframes are aging and expensive to operate. None of that make them good candidates as aggressors, especially when there are so many other air superiority oriented Flanker variants the PLAAF could choose from.
As for using JF17s as aggressors, well that would no doubt be beneficial to training, but setting up the logistics to support a brand new fighter type for a very small number of airframes would make very little sense for the PLAAF. Late model J7Gs are good enough for the role while being very cheap to operate because of the PLAAF's existing large stockpile of spares and large number of already pilots and ground crews who are well qualified to operate and maintain them, and the airframes themselves could easily come free of cost as there are bound to be a lot of J7s going spare as PLAAF units convert to J10s and J11s.