>>537819110
You could try something like this:
logic_case
OnCase01 | spawnpoint* | Disable
OnCase01 | spawnpoint1 | Enable
etc.
then logic_timer that fires PickRandom on the logic_case every 1-5 seconds.

Though keep in mind if you do the exact logic I mentioned above then the order at which everything gets executed is important since it's on the same delay. Would be easier to just have a logic timer that does the following with this snippet of vscript

OnTimer | !self | RunScriptCode | EntFire(`spawnpoint*`,`Disable`,null,-1);EntFire(`spawnpoint`+RandomInt(1,16),`Enable`,null,-1);

since that would guarantee it gets executed in the right order on the same frame. Though it seems odd that it wouldn't just choose a random spawnpoint, but then again I know from experience working with arena that players spawn at spawnpoints in the order they were created, it just usually isn't a problem in regular TF2 due to there being respawn waves and players typically respawning multiple at a time in one frame and thus getting distributed.

This solution isn't great either because two players on opposing teams could spawn at the same location if they respawn at the same time. It'd be better to just spawn them in elsewhere and then instantly teleport them to a random spot in the map. Alternatively you could always just select two random spawns at a time to reduce the likelihood a collision happens. I think TF2 spawnpoints just weren't designed for this sort of game style so you'll need to be a bit creative