i used to have a king betta, he was probably the most relaxed betta we've ever had. he would just cruise around the tank all day and never bother anyone else in the community tank. he was with several assorted livebearers, and they all got along just fine. i'd say that two or three platies would work wonderfully with him in a 10gal, especially if it's live planted.
So remember, when you're feeling very small and insecure,
How amazingly unlikely is your birth,
And pray that there's intelligent life somewhere up in space,
'Cause there's bugger-all down here on Earth.
Loki/Grendel/Gail/Beowulf/Camilla/River/Bathory/Arwen/Lafayette/Deb/Jack Skellington (soon)