You can get Ralph and Felix from RoySquadRocks' OneDrive: https://onedrive.live.com/?cid=CC8ACE125B3A87ED
Ralph and Felix are in the "My MUGEN Characters" directory, a Niceland stage is in the "My MUGEN Stages (1.0)" directory, and (and will probably be announced in Releases when it's done). Roy's version of Q*Bert is also in his Characters directory.
From Bad Anon, Kano ("Cyborg") and Smoke ("Shinobi") can be found in the Mortal Kombat Collection topic, in the Collections section of this very forum. Similarly, loads of Bowsers abound in the topic, and Robotnik can be found in the Collection topic.
Raiu's post in Characters from Wreck-It Ralph movie who are in Mugen. was marked as the answer