However, the majority of those things really don't relate to Pokémon games that much. It doesn't take a year for a person to go through a Pokémon game, and there isn't usually a specific time of year the games get released. It's better off being released in October so people have time to get it before the big holiday rush, and the rush can still push more sales in general. Competition doesn't really matter all that much either as there isn't a lot that's terribly similar to Pokémon games as it is that would directly compete with them.
The only thing I see hindering sales is the transition to the 3DS, which even that isn't that big of a deal as games have shifted hardware before, and it won't the be last the either.