I think the problem with DQ that people seems to have is that...
Erdrick in. No Geno and Sora.
And as what
Tree Gelbman
said, it would be mainly corporate and simply feel off because it’s one of their multiple attempts to get DQ popular in the West. At least with Fire Emblem, Marth was added because he was a very popular request from Japanese fans and they were even thinking about keeping Marth japanese exclusive. But I doubt that Erdrick is actually a popular request for Smash overseas, or anyone that isn’t slime for that matter.
I understand that DQ is iconic, Uber in Japan and, have their history and I actually started to like Erdrick a bit. But it ends up coming at the cost of two other characters that actually have popularity (especially Geno) and one character that is actually liked and well known worldwide. And because of that, Erdrick comes off the wrong way as a “shill” character. Not to mention that people haven’t brought up anything in relation to Erdrick’s potential moveset since that’s also important to Sakurai (unless if I look in the Erdrick thread).
In all honesty, I feel like the Square battle is a never ending cycle and there can’t really be a true winner. If it was up to me, I would’ve tried to get ALL THREE Geno, Erdrick, and Sora since they all have valid points for inclusion.