* Inter-: To indicate something between two or more contestants, as in "inter-school contest"
* Pre-: To indicate something happening before the contest, as in "pre-contest training"
* Post-: To indicate something happening after the contest, as in "post-contest analysis"
* Co-: To indicate something shared by contestants, as in "co-champions"
* Bi-: To indicate a contest between two people or groups, as in "bi-annual contest"
You can also use prefixes to create more specific terms, like:
* Anti-: To indicate opposition to a contest, as in "anti-contest sentiment"
* Pro-: To indicate support for a contest, as in "pro-contest movement"
Ultimately, the best prefix to use depends on the specific context and meaning you want to convey.