Can't do it without faking it with a battle animation. Messages ignore placement within a battle, and pictures can't be displayed normally. The biggest problem with that approach is that the animation will have to be timed, and can't be skipped... and it'll have to be placed correctly. You can use Show Battle Animation in place of the normal text box, in this case.

Edit: Make sure the animation is set to 'global', as well

Also, apparently you cannot remove the battlemenu at the bottom, so the only time you can do this is on turn 0 anyway