User blog comment:JMitch25/Waluigi vs. Harley Quinn - Occasional Rap Battles that Exist/@comment-25872721-20170322111740

Most of the hints point to either Minecraft (Blockhead, definition, Frank Lloyd Wright) or Touhou (Devil's sister, Zune without the e, Bullet Hell). The fact that Freddy was involved with the battle makes me think it's some sort of royale. The only hint I can't make a guess on is Sonic.exe.