Tennessee walkers as dressage horses?

Hi! I have been horse shopping for a dressage and jumping horse. I keep seeing tennessee walkers come up in my searches. So, I was wondering (idk much about gaited breeds), are all tennessee walkers born with only an ability to do thier special gait and can't trot? Because in dressage, the horse would obviously be penalized for not trotting. So, yeah, I'm a bit confused, are they born with a disability to trot, or can you get them to trot like a normal horse?