The ladder was removed because of a general decision (one that has, indeed, been somewhat controversial) by the Other Metagames staff that the metagame was of a lower quality than other OMs with permanent ladders. Though some people disagreed, The Immortal in particular has made it clear that the decision will not be officially reversed.Please Add Hackmons back, It's not even that unbalanced if you know what you're doing.
However, Classic Hackmons still exists as a challenge option. In addition, it will be eligible for Other Metagame of the Month next month, at which point it will get a ladder for the duration of January if it receives a majority of the votes.