Actually... Hal is not developing this game. Hal made the first 2 games but won't be a part of this one at least not directly.
Hal is a 2nd party company. Not a 1st or 3rd party. 2nd party is that grey area... kind of what Rare used to be when they worked strictly for Nintendo but were a seperate company.
Another team is being brought together to create Brawl. It is however being headed by the same guy that did the first 2 games, Masahiro Sakurai. He's also the guy that is responsible for Kirby. I believe this team is going to form another 2nd party company or something like that down the road. For now though they are only scheduled to make Brawl.