That's why interwiki linking helps, and as far as I can tell, MarioWiki isn't linking to SmashWiki at all on their SSB pages.
Fixed!
[Seriously, this is one of those "don't complain about it, change it" things - I've been through most of the major MarioWiki SSB pages over the past week (including Subspace Army & characters), put at least one and frequently more [[SmashWiki:*]] links on each (along with adding links to other relevant NIWA wikis when I remembered, and a few small fixes), and not once has there been a reversion over it. Closest I came was someone not noticing those links, then reverting
himself because "nvm hes puuting links on SmashWiki which is good" before I even noticed it had been changed.]