That's only been a thing for the past 2 years or so, and Rayman is not owned by Nintendo in any way.
Rabbids on the other hand....
Um... Pac-man, Megaman and Sonic are not owned by Nintendo in any way either...
Pac-man has appeared on nearly all consoles (PS3, Xbox 360, PC and Wii U) in his latest game. Nintendo worked out a deal with Namco to put Pac-man in.
Sega currently has a three game contract with Nintendo, which started with Lost World. I THINK there is supposed to be one more exclusive Wii U game after Sonic Boom, but I cannot remember for sure. However, Generations which came out three years ago, was on all platforms. Nintendo worked out a deal with Sega to put Sonic in.
The most recent Megaman game was in 2010 with Megaman 10. This game was on Xbox, Playstation and Wii. There has not been a Megaman game since, but it he is definitely not a Nintendo character. The most recent appearance of Megaman appears to be a crossover with Streetfighter, released on PC only in japan. Nintendo worked out a deal with Capcom to put Megaman in.
Rayman has a super similar story to all these characters. He's appeared on Nintendo consoles a number of times, he's been on the N64, the Gamecube, the Wii and the Wii U. The most recent game was SUPPOSED to be a Wii U exclusive, but obviously Ubisoft changed their minds before release. This may have hurt Rayman's chances of being in Smash, I agree, but to say he doesn't belong because he isn't owned by Nintendo is... ridiculous. And to tell someone they don't know what they are talking about for calling you out is equally so.
tl;dr, Sonic, Megman and Pac-man are in no way Nintendo owned, and vary in how much they are apart of "Nintendo history". Rayman fits into this group just fine, about as much as Snake did.