Prior to the Brawl announcement (2004-the first half of 2006), there was a really divided opinion on who the FE newcomer for Smash Bros. should be (nearly every international lord except Eliwood who was seen as redundant due to Roy already being in, had an almost even amount of support). You had various lords competing with each other for various reasons. Lyn, Erika, Ephraim and Hector and Ike (and later on Michaiah)
Sigurd, despite being a Japan-only lord, also had a devoted and loud fanbase for his inclusion. Due to being yet another sword-wielding lord from a game released a decade ago, you would think they would have a harder time. They spent a lot of their time attacking Roy (and sometimes Ike), and say that Sigurd was planned for Smash 64 and Melee, and that it was originally going to be Sigurd in Melee until IS forced Sakurai to include Roy instead. They also said that Sigurd was Sakurai's favorite FE character and that he was popularly requested for Melee in Japan. His fanbase was nearly all driven by people who loved FE4 and the much darker tone and themes it had relative to nearly other game in the series.
None of these fanbases had a leg up over the other one. While there were a few people that asked for either one of Marth or Roy to be cut (to possibly make room for one of the above characters), most people wanted both characters to stay, and generally disdained the idea of cuts in general (the only two characters in which there existed a modest amount of support to cut were Pichu, Dr Mario, and Young Link)
At the beginning of 2007, there only existed noticeable fanbases for three potential FE newcomers. Ike, Lyn, and Sigurd were all that was left. Sigurd's fanbase was the smallest of the three, but that made up for this by how loud they were and how much they insisted Sigurd was robbed of a spot in Melee by Roy. The Ike fanbase was slowly regaining their strength due to the information that Ike was set to return in FE10.
The second half of 2007 proved to be very chaotic and war-like much like it had been a year before when Brawl was unveiled. There were a bunch of profound developments that would unfold that would drastically change the landscape for the FE character representation wars.
The Sigurd fanbase, during all this time was being depreciated, they were not being attacked by other supporters, but for most people, if a Japan-only blue-haired swordsmen were to be in, it would be Marth. Nevertheless, the Sigurd fanbase continued to use the same arguments that he was planned since Smash 64, and that he and his game were more popular than Marth in Japan.
At the beginning of August 2007, the first newcomer since the unveil in May 2006 had finally been confirmed, IT WAS IKE! The Ike fans were ecstatic and after a long fought and bitter batter for nearly two years, they were finally vindicated, and for the the supporters of other male characters in competition with a female character (Wolf vs. Krystal, Toon Link vs. Midna), it meant that perhaps Sakurai would look at other qualifications for a character besides whether they had boobs or not.
In October, two profound developments happened. One was the announcement of FE11, a remake of FE1 which had Marth as the lord. It was here that most Smash Bros. fans felt that Marth's return was now likely. The argument that Marth was "no longer relevant" or "Japan only" now no longer applied. By now the Sigurd fanbase was weakening heavily, the confirmation of FE11 and many people believing Marth was likely to return, gave people no taste for three blue-haired swordsmen. Sigurd fans tried to beat the same drums as they had all along, however, like Lyn, they too would be de-confirmed, only this time by the hands of a fan, not Sakurai.
A Smash Bros. fan translated Sakurai's pre-Melee poll, and some of the statements that Sakurai made in his pre-Melee journal.
His findings were:
1. That the only characters planned for Smash 64 that did not get in were King Dedede, Bowser, and Mewtwo.
2. That according to the pre-Melee poll, Sigurd only received a measly two votes (the same amount as Leaf), while Celice had four, and non-lord Ogma/Oguma received eight votes. Marth by far stomped every other FE character in terms of votes.
3. Sakurai brought up who his favorite FE character was. It was Nabarl/Navarre, a mercenary from Marth's games.
The publication also of sales data from Japan that showed FE3 having sold more than FE4 (as well as FE6 being the third highest selling game in the series overall), further disproved the "Sigurd is incredibly popular in Japan" argument.
Roy and Micaiah fans paraded this information around whenever Sigurd was brought up, and this permanently ended the Sigurd fanbase. Many Smash Bros. fans were disgusted how much of Sigurd's support was based around lies.