Like other have said, Pit does best when he can camp below platforms & just juggle with Uair and Usmash.
For starters, try battlefield, lylat (or dreamland if that's a starter), and smashville. Lylat is a slightly more risky pick, however, as it's very easy to SD with Pit's upB if you angle it incorrectly.
It's probably best to ban FD and T&C in order to get the stages with no/high platforms out of the way.
Choosing a counterpick is a little harder. If dreamland is a counterpick, you could always go with that because its so similar to battlefield (3 platform layout still benefits pit). If Halberd is legal, it can be pit's most powerful counterpick because of how easy it is to juggle from beneath the central platform & because of the low ceiling.
