none of thier skills really matter, let me sum this up mathematically.
asajj has 2 lightsabers
+
grevous has 4 lightsabers
+
maul has 2 lightsabers
_______________________________
between the 3 of them they have 8 lightsabers
this means with 3 of them they have to either attack him at once (in which case he pwns them individualy via the force) or they attack altogther and cut each other up with 8 blades and limited room.
either way it looks good for dooku