Mario and Luigi get ***** by high tiers like Snake and Metaknight, are you kidding me? At least luigi can kill the characters at lower percents, same with Ike. I really hope you aren't being serious about Boss's Mario beating high level MKs. Mario has the tools to beat most of mid tier, until he gets to characters that can outspace him, then he gets *****. Ike has the ability to outspace characters, and has matchups that are relatively manageable in the A tier section (Snake in particular).
Until Boss plays those people, then we can't say Ike is ~= Mario.
By the way, Ness is still considered low tier for low tier tournaments, just because he's mid tier in the tier list, doesn't mean he's mid tier in the eyes of BBR. He's good enough to stand out from low tiers, however not good enough to compete with mids.