When a poodle has a good confirmation, it means that there is less likely to be strain put on different parts of the body by faults on another part. Poodles should be short bodied and square, ie as tall as long. A long body is less of a problem for an agility dog, so long as they have good hind quarters. I believe that temperament is more important than confirmation. You need your dog to be obedient but have enough confidence to tackle all the equipment and to keep on going without you close by their side. The main thing is that the dog should enjoy what they are doing.
Inca was in the show ring until she was 18 months old but, in my opinion, her temperament was more suited to agility. She always wanted to be doing and it was difficult to keep all 4 legs on the ground. Even when she saw the agility equipment for the first time, she was more than willing to tackle anything that was put in front of her. Coco, on the other hand, is more interested in sitting on knees, chasing balls and generally being loved. Two dogs, both happy in what they are doing!