What is the compelling reason to test Shaymin first?
It seems to me that the fact that we have had it longer is a pretty logical reason to do this, especially since you are talking about having a 2 month testing period because of this fact. Have two one month testing periods and we are more consistant, and we do twice as much testing in the same amount of time.
I think that we should test Deoxys first because Deoxys is the more broken of the two.
Also the point of interplay between Deoxys and Shaymin is kinda weak in my opinion as Shaymin is one of the few pokemon that with a Scarf can outspeed Deoxys, and it does 84.3% min to min SDef 1hp Deoxys with Seed Flare (which basically means it will always KO in any reasonable situation).
Now, if we find that Shaymin works great with dx-s present... and we subsequently ban dx-s and that changes the situation enough that we need to revisit Shaymin... fine. This is a more careful approach than testing dx-s first.
This doesnt really make sense to me, it seems like it adds in an unnecessary step. If we find Deoxys is Uber, then I dont see how the fact that it counters Shaymin makes it any less Uber. So by testing that first, we can test Shaymin without having to repeat the process. What is careless about this approach? Though to be fair this is totally irellevant, since Shaymin can counter Deoxys anyway.
Furthermore we have some concept of life with Deoxys but without Shaymin, but if we test Shaymin first then we will have no idea of the opposite.
Honestly I really feel testing Shaymin first is a bad idea.
And as for the voting bias I think this is not a reasonable way of doing this. It is like saying people cant have as much information as possible before casting their votes because doing so might help them make a decision. If you dont trust people to not be biased, then you shouldnt let them vote.
I dont see how it makes a difference anyway. The only reason you got involved in the last vote was because you were sick of battling Garchomps. I know I had some preconceived notions before the test, but I also didnt witness anything that was contrary to those notions. I think ultimately if we have a vote we have to trust people to vote properly.
Also, why is it so obvious that peoples arbitrary biases will increase over time? It seems counter-intuitive to me. It also seems unlikely that peoples biases start after the initial introduction of a pokemon, unless they are actually based on some kind of experience. I dont see people becoming biased based on irellevant nonsense within the month it will take us to test Deoxys. I do see a lot of ridiculous hype and novelty value decreasing which suggests to me that the Shaymin vote should take place after the Deoxys vote.
Have a nice day.