This is a topic that I have covered previously (Daily and Warm Up Exercises) And Most likely will do so again in the future but today i want to present a quick routine aimed at development athletes
Warm ups will change depending on the group or sport and the training session that you have planned but with development athletes one of the main focuses has to be teaching correct movement and building good habits with these movements
Working with athletes from 11 years and upwards, I want to instill a correct understanding of core engagement as well blending this engagement with movement and mobility.
There are many exercises we can use to achieve the same outcome but 3 I like to use are laid out below

All of these exercises can be upgraded as the athletes get more accustomed and proficient at them and we can layer in improved movements as well. For example the Wall Press Abs can start with one or two legs in a cycle type motion or a straight up and down core extension.
But if you have a development athlete looking to get a better warm get them started on this and see how they respond