I remember seeing one episode where they questioned whether Hamada was still a Tsukkomi. They said that over the years he became more and more of a Boke. They didn't know if it was something on purpose, or because of age, as he got older and more senile. Or who knows, when they are in a "group", they all end up going Boke, for the entertainment of the public. I've seen many Tsukkomi's be "funnier" than their Boke's partners... So I believe that these terms no longer apply to groups of comedians. The two can be Tsukkomi's, or Boke's.
GakiNoTsukai
Downtown no Gaki no Tsukai ya Arahende!! is a Japanese variety show which stars comedians Matsumoto Hitoshi, Hamada Masatoshi, Tsukitei (Yamasaki) Hōsei, Tanaka Naoki and Endō Shōzō. It is best known to western audiences for the annual No-Laughing Batsu Games and the original version of Silent Library.
Submissions aren't limited to just Downtown no Gaki no Tsukai ya Arahende!!, you can post anything related to the members of Downtown, Cocorico and Tsukitei Hōsei.
The tradition manzai roles do not apply on Gaki because the 5 are just playing off each other. There are not defined roles for them on the show.
Cocorico pretty much adheres to the senpai/kohai relationship with Downtown. Even though they don't have a lot of subs, I think they were smart to make a Youtube channel to remind people they exist as a duo outside of Gaki.
cocorico are more of a sketch group than manzai