The 10 Great Warriors (also known as the 10 Great Family Heads in modern Tower society) were incredibly powerful warriors who entered the Tower along with the Great King Zahard. They are all technically Irregulars, but they are not considered so. They are the founders and heads of the 10 Great Families, and as a result possess great political power and combat prowess. They are among the strongest Rankers in the Tower, a few of them being within the Top 10 High Rankers, and it's likely they're all within the Top 50 High Rankers.
It is worth noting that Zahard and the 10 Great Warriors were not alone in climbing The Tower. They had helpers including Grace Mircea Luslec and several Princesses. It seems that some or all of the helpers only joined them after the climb had covered a considerable amount of Floors. As an example: Luslec was born on the 80th Floor and had most likely not taken part of the climb until after this Floor.