[hanniabu]

Also your opponent would have an advantage of you being lighter, which affects the results

[sfn42]

Normally in weight classed sports, people cut and dehydrate etc so that they are just inside the weight class they want to be in.

In other words, if they didn't cut they wouldn't be meeting that opponent at all because they would be in a different weight class.

[candiodari]

Except both you and your opponent would be using tricks to be lighter (e.g. not drinking at least 1 day before the weighing)