Having also obtained reqs a little while ago, I guess the time has come to outline my thoughts.
The Suspect Ladder previewed a meta with Sableye only banned, and bar the million geniuses running some variant of stall on ladder, some interesting trends were noticed. Primarily, from laddering on multiple alts, I found that there was a good amount of variety without M-Sableye, as some others have mentioned. Balance breakers such as Mega Medicham, Mega Alakazam, Mega Scizor, Mega Pinsir, and Mega Metagross were commonplace on ladder, and considering that a significant portion of people on ladder had TankChomp as their check-all Pokemon, this was no surprise.
Onto the argument on whether Sablenite should be banned.
First of all, I should preface by saying that I had no personal preference between the Suspect Ladder meta and the regular meta. As many others (including
bludz, who made an excellent post in this thread), Sableye is not uncompetitive, and to save time, I will not reiterate the points that were already made well. Hence, the question that presents itself relates to whether M-Sableye is unhealthy/broken. This is where things begin to get slightly sketchy, as it is difficult to present an objective view on this issue, so I will try to isolate the components that make a Pokemon broken or unhealthy, using the
OU Tiering Policy as a reference point, without trying to influence anyone else's opinions.
Upon examination of the text, the main attribute of a broken Pokemon is its ability to
"Limit Teambuilding Skill". Does M-Sableye fulfill this criteria? Personally, I do not think this is the case, as this attribute usually necessitates the use of uncommon Pokemon whose implementation would put the rest of the team at a disadvantage in checking other threats. With its checks including common Pokemon such as Heatran, Manaphy, Clefable, Talonflame and Keldeo, to name a few, I do not think this is the case.
Hence, the second argument, is Sableye unhealthy? This is much more subjective than the previous criterion, as each user would have their own definition of what unhealthy means; the policy itself defines unhealthy as,
"elements that are neither uncompetitive nor broken, yet deemed undesirable for the metagame such that they inhibit "skillful play" to a large extent". Is Mega Sableye unhealthy? As previously mentioned, this is subjective; you may agree or disagree with the definition outlined by the policy, so I will leave this up to you to decide for yourself. In my opinion, using the aforementioned definition, I would state that it is not unhealthy, for the reason that it does not inhibit skillful play as far as I could see.
Using the aforementioned criteria, it seems that Shadow Tag could fulfill both criteria, as it can
limit teambuilding skill and
inhibit skillful play. Examples of this include being forced to run sets such as Shed Shell Manaphy, and in general, doing the Samba in every Pokemon battle against Gothitelle stall to prevent Sableye checks such as Keldeo and Clefable from functioning effectively.
Hence, I believe that since, in my opinion, those criteria are fulfilled, I believe that
Shadow Tag should be banned.
As always, I end by stating that this is my view and others have their prerogative to disagree with the said viewpoint.