>>32648332First, you need to realize there is a single true format, which is 6v6 Anything Goes. All other formats except maybe VGC is autistic bullshit.
Stall is bad because it doesn't work well with the single best pokemon in the game- Mega Rayquaza.
Mega Rayquaza singlehandedly beats 99% of all stall teams. What the hell does a stall player do when Mega-Fug starts spamming Dragon-Dance boosted Dragon Ascents and Outrages while holding a Lum Berry? Sure, you could try Skarmory or something but they can carry moves for that too. What if it's mixed Rayquaza?
For that matter, what use for Mega Rayquaza does stall have? Is it really a stall team if it intends to win by attacking with Rayquaza? Would that just be a really, really defensive Balance team?
The fact of the matter is, stall only works at all in formats where highly effective wallbreakers (most box legends and a good portion of smogon's BL lists for their lower tiers) are banned. IF you weren't supposed to have/use these powerful wallbreakers like Mega Fug and Palkia and Yveltal, then why would GF eve make them catchable in the first place? Stall is an aberration, an unnatural playstyle not intended by the makers of the game.