Nuzlocke-Challenge is the largest (and first) group on deviantArt devoted to showcasing Nuzlocke fan runs of all kinds. It was founded on August 31st, 2010 by dA user iuuai, and currently has over 2,100 members and over 17,000 submissions.
It is the main hub of Nuzlocke activity outside of the Nuzlocke forums.
Nuzlocke-Challenge is a generic, catch-all Nuzlocke group, as opposed to a Nuzlocke fan group or specialty Nuzlocke group.
The group was officially founded by iuuai with the help of her friend octopuddle. The group eventually became too large for the two of them to run, though, creating massive backlogs for submissions.
As such, in February of 20121, they opened the floor to mod applications, and ultimately selected four new members to become "co-founders"2. While the list of active mods has shuffled a bit since, backlogs have essentially been eliminated, and group events (see below) are common.
The group successfully maxed out dA's folder capacity for the original "Comics" folder in April of 2012, and then filled the new "Comics 2" folder by early March 2013, suggesting the group is not only growing with time, but growing faster with time.
Nuzlocke runs are sorted by type (comic or literature; screenshot runs fall under comics, as do any video updates), with extra folders for rule lists, artwork, prologues of either type, and background information. Non-Nuzlocke folders include journals by group members and group-event-related submissions.3