I've seen a mod called shaolinsoccer using this, if the ball touched the net, then tori would win, but if tori touched the ball with his hands, uke would win, but how do you do this exactly? It doesn't appear anywhere on the modmaker options

I haven't used modmaker much recently but I just checked it out. The trigger system looks kinda complicated so maybe someone else can explain it better but nobody has replied so I'll give it shot.

When you have an object selected, check "Enable Trigger System." Then assign it to a group. I'm guessing the groups are additive (i.e. if you check just group 1, it's group 1, if you check groups 2 and 4, it's group 6, etc...). Then click one of Tori or Uke's hands and go to Body II page. Check "Enable Trigger System" here again and assign it a group as well. Then next to "Collide With," select the group number that you assigned to the environment object. Next to "Trigger Action," select the player that should win when these objects collide.

For two environment objects colliding it's pretty similar, except instead of clicking Tori/Uke's hands you select the other environment object.