What kind of bikes can be used for different cycling events

One Bike to Rule Them All (...well at least for road, gravel, and cyclocross)

With USA Cycling's 2023 rule change moving a way from junior road gearing requirement, juniors no longer will have to conduct a bike roll out check at road events. This essentially means that an athlete will be able to use one bike with clearance for gravel, road, and cyclocross tires for all of these events if they wish to do so. The recommendation here would be to swap the tires for the cycling specific event tire which is much more reasonable in cost then having three different bikes.  

For the other cycling events it is required to have a 1:1 match, bike to cycling event:

Track Racing = Track Bike 
Cross Country Racing = XC Bike
Downhill Racing = DH Bike 
BMX Racing = BMX Bike