506.3 Only a creature can attack or block. Only a player, a planeswalker, or a battle can be attacked.
506.3a
If an effect would put a noncreature permanent onto the battlefield attacking or blocking, the permanent does enter the battlefield but it’s never considered to be an attacking or blocking permanent.
506.3b
If an effect would put a creature onto the battlefield attacking under the control of any player except an attacking player, that creature does enter the battlefield, but it’s never considered to be an attacking creature.
506.3c
If an effect would put a creature onto the battlefield attacking either a player not in the game or a permanent that’s no longer on the battlefield or isn’t either a planeswalker or a battle, that creature does enter the battlefield, but it’s never considered to be an attacking creature. See rule 508.4a.
(refs: 508.4a)
506.3d
If an effect puts a creature onto the battlefield attacking during the declare blockers step, combat damage step, or end of combat step, that creature enters the battlefield unblocked. See rule 508.4d.
(refs: 508.4d)
506.3e
If an effect would put a creature onto the battlefield blocking but the creature it would block isn’t attacking the entering creature’s controller, a planeswalker that player controls, or a battle that player protects, that creature does enter the battlefield, but it’s never considered to be a blocking creature.
506.3f
If an effect would put a creature that’s also a battle onto the battlefield attacking or blocking, that permanent enters the battlefield but it’s never considered to be an attacking or blocking creature.
506.3g
If a resolving spell or ability would cause a battle to become an attacking or blocking creature, that part of the effect does nothing.