We've done all-support team comps every so often with Winterwind, Bunny_of_Faith, Adumbration & co. They work extremely well. Actually, in one of those Riot vs. Pros show matches, Riot made the mistake of making Pros play an all-support team. I'm not sure if the Pros had any deaths
AD Sona is amazing and I maintain she's actually legit. Janna's AP ratios got gutted but she's still okay. She also works AD. Taric's fine AP, Alistar's great AD. Lulu is great as...anything.
Last time we ran Sona/Nidalee bot, Lulu top, Janna mid & Taric jungle. Obviously not Alistar jungle since that's just too easy.