They would still teach them how to stand and they would still start at the very beginning.
Transitioning from style to another doesn’t automatically allow you to skip over the basics. In fact, the basics become that much more important. All martial training is a re-training of the body’s natural responses and muscle memory is very confusing. Doing one will not necessarily allow you to jumpstart into another. You’re actually much more likely to fall prey to the minutiae. Getting caught between a technique in one style and the technical details of another will lead to confusion during a fight. It’s a costly mistake, a deadly one. In some ways, it’s faster to train someone who has already been trained in another style because they grasp the concepts faster. However, it’s also slower because you also have to retrain or find a way to harmonize their body’s now natural responses with this new style. Even for two styles that are very similar, the differences can be vast and the last thing anyone wants is to see their student die because they decided to skip necessary steps.
The early stages of training are the most important.
I said it in the other post, each style has their own unique way of going about training and everything is slightly different. Those differences can create drastic flaws in the techniques that they’ll be trained in if they’re not corrected. You can never completely rewrite their foundation, but they still have to learn the new rules in the same way that any student would.
If you’re going to write a student of two different martial arts styles, then you’re going to be beholden to both of them. Thorough research will be needed on one and then the other in order to understand the transition and the conflicts between the two styles when it comes to training in more than one. This is also why it’s best to do one and then the other rather than two at the same time, two will lead to conflicting signals and constantly force them to unlearn what their body recently learned which sets back their progress. Unless the student works very hard to assert the second style as primary, the first one they’ve learned will always make up their “base”. This will be true even if they don’t use the skills at all as the stylistic tendencies inform their body’s movements. These qualities become more apparent within an individual style due to the proclivities of different teachers. It extends beyond just martial arts too and into other physical activities, a character raised in ballet will still subconsciously carry themselves like a ballerina even after they’ve switched over.
And, sometimes, even in the same style when switching to an additional discipline such as a weapon discipline will also return to basics. The student will spend the first day learning how to stand with a sword, hold a sword, and balance a sword in their hands long before they start learning the techniques.
The basics of training work like this:
Learn to stand.
Learn single techniques while standing without stances.
Learn to move in single line in stances with no techniques.
Learn single techniques in conjunction with stances.
Practice moving forward while doing technique in stance until student becomes comfortable with single technique.
Put techniques together into combination of different moves. Have students practice in a single line.
Teach students “form” comprised of techniques, which includes transitions into multiple different angles and turns.
A basic beginner form from Taekwondo would be:
Stand in beginning stance/ready position facing instructor. Turn left into basic fighting stance, slide front kick into double punch. Hold. Breathe. Turn right into basic fighting stance, slide front kick into double punch. Step back to turn toward instructor into fighting stance, front kick, front kick, front kick into double punch. The whole of the form takes place on a T shape rather than a single line.
As training progresses, include more complexity i.e. different stances and kicks. Always return to beginning when adding additional training or new concepts.
There are plenty of aspects of martial training which can (and often are) short changed in order to speed students through the process, especially when they’re on a condensed schedule with a limited amount of time. The basics are not one of those things. A broken base leads to a broken trainee.
Basics are what save your life.