Not to come off as a dick or anything, but a lot of your post is just wrong.
Scarfed Modest Latios isn't a great set at all, you want to keep Timid so you can outspeed stuff like ZardX at +1 or Scarfed Keldeo, and LO hits harder anyway
Sableye can't stop Landorus because it gets destroyed by an Earth Power, and it can't Mega Evo because it's the no mega ladder.
Xatu just sucks and it just gets hit by Knock Off, HP Ice or Rock Slide. I don't even think it can take Sludge Waves very well
I don't see what your magmortar comparison is supposed to mean, it doesn't have a great defensive typing, it's weak to SR, it doesn't have Sheer Force, it's kinda slow, it can't boost or anything.
Abomasnow is not a counter at all, a counter needs to be able to switch into it's most powerful coverage move and then force it out. Abomasnow isn't switching into Sludge Wave and nothing stops Lando from coming back in
Haunter already mentioned that there will be no suspect tests for this meta, but just bans.