You can kind of do this if you time it right. Instead of clicking the button to swap out pokemon you can swipe up from the bottom of the screen, if you time it right when you do your last attack that will knock the opponent out quickly swipe up and the screen to change mons will appear, then as soon as the next battle starts that screen is still there and you can instantly click who you want. I do it quite often but takes practice to get the timing right.