Do anything and everything you can. Share artwork, move-set ideas, videos explaining the characters history and legacy. Pictures are always better than simple text. Pictures get the idea across very well. K. Rools move-set is near identical to many of the fan-made move-sets that were circulating in 2014-2015. The great people over in the K. Rool thread all had their own way of spreading the news. As for myself, I'd take whatever fan-art was posted on our thread and Tweet it to Sakurai, Nintendo, Playtonic..etc. It was quite a bit different with the ballot running around. I'd put in dozens of votes in every day if I could for the character. I made everyone I know do the same.
Over time, it became more of a, "Let your voice be heard" movement. Many of us started posting #KrocTheVote to any and all social media sites. There was a few months where I went around to the most popular Youtube and Twitter speculators and asked them what they thought of K. Rools absence, and if they wanted him or didn't want him; while at the same time posting a welcome message to any readers to join our movement of wanting the King to return. Some Youtubers helped by making it known that they wanted him or by expressing their confusion as to why he was not in yet (in video), others said they would help with Top 10 lists and what not.
Just spread the word anyway you can. People don't want a character if they don't know anything about them, and until the ballot started, K. Rool was a "never going to happen/irrelevant" character. We have been shown that we couldn't have been further from the truth after Nintendo clearly saw how badly he was missed. Now he will be known by everyone who plays Smash Ultimate. Feels good. He is back in the spotlight next to DK where he belongs. Hell, maybe he'll team up with Bowser some day near or far. P.S. I just can't wait to see him back in the DK franchise, because at this point, it is inevitable.