Originally Posted by Tnavas
All the warmbloods have a draft horse somewhere in their pedigree - that is how the term Warmblood came about - the cross between a draft (Coldblood) and a TB or Arabian (Hotblood)
Yes, but so many generations back that they can hardly even be traced back to them. Even now only arabian and TB blood can be added to warmblood lines. By now they are very distinct and breeds in their own right.
Warmbloods have also been specially bred to do dressage or jumpers, to the point where you can look at their pedigree and say what they're bred for. Getting a larger warmblood for dressage would certainly be easier if you plan on doing higher level dressage, as there will be a much larger pool of appropriate horses, but draft crosses can certainly have their merits.
However, if you want to get a draft cross that would excel you'll probably have to do a little more research, as you'll need one that was specifically and carefully bred to be a high end sports horse.
Of course, if you don't plan on doing higher levels then you can really select any horse you'd like.