Just adding another opinion on the chandelure debate.
Lucaroark, I think the point you make is a very valid one, in that if countering something requires that you have at least one of such a small list of pokemon (2), this perhaps begins to lean towards overcentralization. Of course, the cut-off point between "threat that every team should prepare for" and "over-powered threat such that extreme specification is needed to counter it" is rather ambiguous, but there is something that is important to note. Metagames have their own "flavors", including what team styles and strategies are popular, but also including what common pokemon are. Of course, a huge facet of DW's "flavor" is tyranitar's immense popularity, which substantially decreases chandelure's usefulness. Is this necessarily over-centralization? I don't think so, since tyranitar has a huge amount to recommend it without including its status as a chandelure check. Would chandelure be broken if tyranitar weren't so popular? Maybe, I would probably say yes--requiring something like snorlax on every team IS, IMO, over-centralization. But requiring tyranitar doesn't seem like broken to me at all--when i built my team, chandy wasn't even on my mind when i selected SS and ttar. To make a parallel, there are pokemon such as solar power charizard that are every bit powerful enough to merit being OU, but that are held back because of their stealth rock weakness and the fact that is on practically every team, dropping them down to UU. Volcarona might be pretty much impossible to deal with if not for stealth rock's ubiquity, but with it volcarona is nowhere near broken. tl;dr, whatever potential brokenness chandelure might have, the metagame is so adapted to it that it is not broken. If the metagame were to change with ttar suddenly dropping in usage (i doubt it), perhaps then it would be broken, but IMO, atm it is not.