The unfortunate part of this is you can say literally any popular character in terms of discussion. Reimu, Hayabusa, Dante, Crash, 2B, Sora, Rex, Arle, Geno, Llyod, Dixie and Phoenix Wright all have their fans and get talked about fairly consistently.
If you wanted to bring up someone who's not discussed much, say Arthur or Bill/Lance, but you won't really get far with people. There's a few people in the middle ground of this, like Lara Croft or Sol Badguy. And every time Mortal Kombat's been mentioned, it gets shut down immediately. Killer Instinct probably ain't happenin', cause of 2 Microsoft characters being in already, unless we get really lucky.
Then there's stuff like League of Legends, is hugely popular, but has a ton of characters, so unless your pretty familiar with that series and its characters discussion surrounding it will be weird.
But with Heihachi's Mii Costume, people don't really feel the need to bring up Tekken like before, even if technically Jin and Kazuya could be viable. Soul Calibur gets a shout out every once in a while, but unfortunately doesn't have a huge pull with Nintendo fans.
People aren't gonna think about shilling for Raziel or any lesser-known character unless a leak pops up or you get an obscure character to organically get attention in the Smash fanbase's faces. But again, without leaks, doing so for a Non-Nintendo obscure character seems really unlikely without it being an intentional joke.