Hmm... what happens if you give a boss the MF_PUSHABLE flag? I may test this, depending on if socedit runs in Wine.... I'll edit my findings in.
EDIT: Well, basically the boss doesn't move at first, but will still damage the player, when the player moves near the boss the boss 'attaches' himself onto the player, following it around, when the player moves too fast for the boss to keep up, the boss will continue moving in the direction it was last moving in until the player moves near again. If the player hits the boss, the boss will become stuck in his painstate and become invincible and undefeatable. Sorry, I don't think you'll be able to teleport a boss any time soon...
EDIT2/Note: Enemies, while still doing the annoying 'attach', will still operate while pushable.