Train your horse at home without spurs or whip. And at the show with spurs or whip. So he can’t get used to it.
Work on it at home first, transitions, transitions, getting them a bit hotter so then you’ll be able to take that into the show ring. Naturally they’re hotter at shows.
I think spurs but if it’s that lazy and your horse refuses try both.
Spurs would be the better answer in the show ring, they're more invisible than a whip. Depends what you're showing in and how your horse reacts to the different things. Try them at home first and see what works