Japan is the strongest Nation in Brawl.
I've been talking about this with JJWolf and TKD before and we all aknowledged that Japan has the best Brawl players. This has nothing - or very little - to do with how well Brood performed at Apex because we all shared this opinion before Apex. If anything proves the strength of Japan in Brawl it's Sweet Pea's placing at Apex. Nobody I have talked to - all people that, like myself, have extensively concerned themselves with japanese Brawl - have ever heard of him before. From what I've heard on the stream and from people who played him he's playing Meta Knight but in Japan he is probably considered a "random". Ask around for japanese MK players and the names you will hear first are the likes of Akira, Ootori, L, Eru or Shikkoku.
Sweet Pea? Never heard of him before. And yet he is able to tie at Apex with the likes of Gnes (considered 2nd best US Diddy) and Malcolm (top 3 Wario in the US) beating the likes of MintyFlesh (top 5 Marth) and Logic (top 3 Olimar) in the process.
Brood. After Apex there is no doubt that he is the best Olimar in the world. He places 2nd/266 in Brawl singles being only the 2nd player in the history of Brawl to beat Ally and M2K at the same tourney. One thing people didn't seem to take note of yet:
He doesn't do as well at Japanese tourneys.
He never places above 3rd in Japan and even then he placing 3rd is a considerable achievment for him. Just to be clear: these are not "national" tournaments with the size of Apex - they never have 266 entrants. These are medium sized tournaments of about 50 players, which is not even a quarter of the Apex attendance. And he still is unable to make a showing there in the way he does at Apex.
Keep in mind that during all that, Brood had to deal with an unfair ruleset (uncompetitive stages like Brinstar and Rainbow Cruise, only 8 minute timer), that they were not used to. In Japan the stages favour Olimar a lot more than in the US but that also didn't keep him from doing better than he does in "random" japanese tourneys.
In several cases japanese players are the best in the world with their characers:
Smasher for Toon Link
Brood for Olimar
Ocean for ROB
Kakera for Ice Climbers
Masashi for Pit
Earth for Sheik (Jujux might be a better Zelda though)
Even if an american player (or european player in case of Glutonny) is considered the #1 for a character there are often one or more japanese players close behind. Mew2King is clearly the best Meta Knight but after that there's at least 3 MKs that give the US Top MKs (which are Lee, Anti and Tyrant atm) a run for their money, Akira being probably better than all of them (except M2K himself).
Dehf has established himself as the best Falco but not only is Rain close behind but he also leaves the rest of the Falco's far behind too. The best example for this however is without a doubt Snake: Ally is still the best Snake even though he might have hit a "low" now. After that: all japanese; Shuu, Souther, Hiko, Shuya - these people are probably all as good, if not better than the next best US Snake.
Japan has so many great unknown players, it's as if they had no "random" players because they are all great at powershielding and buffering - something only the top players in the US or the EU do.
Edit: despite all this I still think M2K is the best player in the world in Brawl.