Can you dention sphere a plainswalker or a god
{Detention Sphere}
Planeswalkers are nonland permanents, as are gods (which are all enchantment creatures).
No planeswalker or god is named Detention Sphere.
Therefore, the only issue is whether the planeswalker or god is targetable. Unless they have hexproof, shroud, protection from white or blue, or protection from enchantments, they are targetable by Detention Sphere.
Hope this answers your question.
What about if there indestructible
Being indestructible does not contradict any of the criteria required for {Detention Sphere}, since nothing is being destroyed.
Basically, something indestructible can still be exiled.
I think he was talking about creatures with plainswalk, not planeswalkers! :P