1) Does the clauses change every round?
The clauses do not change.
2) Why is baton passing to marowak banned when BPing to medicham isn't?
I did not make these rules, I lifted them straight from koudai8.
3) How can you check if the dugtrio has arena trap or sand veil?
Check to see if you can switch out.
4) Same goes for Blissey and serene grace
Well, it shouldn't be too hard to determine if Blissey has Natural Cure or not.
5) I find it ironic that DDtar is banned, when DDsala and DDgyara are not.
This isn't a question that I can respond to.