RS200-yes it was a Group B car. however, it was not dominate, though if there had been an '87 season, it probably would have won. Ford introduced the car for the '86 season (i think technically it was at rally GB of '85, but whatever). while it had some success, it showed quite a bit of potential, though it wasn't up to the level of the Peugot 405 T16 or Lancia Delta S4. however, for the '87 season, Ford planned for an evolution edition that was to have about 150 extra ponies (which would have been around 650+) and, more importantly, significantly less weight (the RS200 was a bit of a porker). also of note, Ferrari planned to run a 208 GTO Evolution on the tarmac events. now that would have been a site to see

that car actually became the basis for the Le Mans winning F40.
Lancia Statos-that was the car to beat in the mid to late 70s. this was becuase it was the first car built with rallying as its sole purpose. however, it made only around 250hp and was RWD. it was no GrB car. once Audi introduce AWD in 1980, it was all over for the stratos. however, Lancia did have success with the stratos's replacement, the 037, even though it was still RWD.
the stratos was one badass looking car