lol chatot
Talk to any of the old UU guys, and I was repping Chatot about as hard as one can back in the day. I even wrote the current Chatot analysis. Its defenses suck, but it has solid offense from a 92 Special Attack, and a trolly 91 Speed means that it outspeeds Moltres easy mode. I believe the set that I used was Plot / Voice / HWave / HP Water. Encore is iffy at best when your opponent's best bet is "switch", but there are a lot of competent Encore users to bait attacks aimed at Chatot.
I might try it out again in this meta, but I see it having issues. Dugtrio = get fucked Chansey, but the analysis 252/156 Careful Registeel takes 71-83% from +2 Heat Wave, and gets TWaved in return (i guess dugtrio deals with registeel but w/e). Rhyperior takes it from HP Water, but Regirock lives HP Water just as well as Registeel does (if it runs something sdef-y), Lanturn owns Chatot (again dugtrio i guess), and there's also Raikou (dugtrio but now we're getting over-reliant), Drapion, Houndoom, really anything 95 and up is causing issues and they're all over the place.
I can't see myself using Chatot seriously without a buttload of support, and even then I can't see why I would want to use it over something like Nasty Plot Mismagius.