I have thought about similar things intensively quite a while ago, and honestly, I don't see a useful way to do this in context of the champion's cup.
The first and most important problem is the effect of healing items. Even with coordinated high end attacks, it can be difficult to take down a character that has a good supply of such items. Health caps are indeed low for some choices of character creation, but the limitations to inflict damage are much more (equally) pronounced at this stage.
The second and obvious problem is how exactly to define the restriction of an "untrained" character. The only fair way of handling this is to allow characters of exactly the same race and quick character creation path. With those paths and no further training, magic cannot be used in any reasonable way, unless you allow the use of certain precious skill boosters. Also, with standard quality weapons, it takes quite a few hits for such characters to take down each other, as chances to miss are annoyingly high. I don't think that you want to announce a general cap like 100 for all stats and 20 for all skills, which will result in players opt character creation and training to breed an army of alts that hit exactly the given limits.