As to why /b/ dislikes Mudkips, it's because /b/ is composed mostly of insecure men.
Here we have someone, this Mudkip: who is a Mudkip and is therefore somehow in our vertical, whose cultural sensibilities we find tacky, who has a group of admirers that we don't have.
Despite all this:
physically, Mudkips are out of our league. They wouldn't give most of us the time of day and we know it. nonetheless, we're still attracted to them. they're rich and entitled, while most of us will never be.
It's this tension -- that we think they're hot despite ourselves -- which creates the drive to attack them. If we can "defeat" Mudkips, the thinking goes, we can defeat this ugly contradiction.