Four of them are summoned in the Skeleton Lord Boss Fight.
They are identical to their Dark Souls counterparts in terms of appearance.
The Bonewheel Skeletons in Dark Souls II are almost exactly the same as they were in Dark Souls so the same tactics will be just as viable. They are easier this time around, however, as the number of times they hit upon colliding with a player has been lessened and no longer stunlock as hard as they used to.
However, it is to be noted that this time around the Bonewheel Skeletons are capable of quicker turns and righting themselves after a missed attack, whereas their counterparts from Dark Souls would continue rolling for several seconds and take a few more to turn around. These Bonewheels are capable of attack and turning around in under a few short seconds. A weapon that does over 150 damage per strike can kill them in two hits and a weapon that is enchanted can do the trick in one. A +5 -+7 single handed weapon works just fine. They are also very vulnerable to fire.