When it comes to stretching, no it's not or shouldn't be. If they are young enough, we can get them just as flexible in the shoulders and backs as the girls and hips possibly.
Conditioning wise there is a lot more focus on building a strong support and being stronger through the middle and upper body. A good support is necessary to even do the basics of horse and is very challenging on rings. A tap swing on rings requires more strength and develops more strength than one on bars.
Also boys are required to develop a pirouette earlier than girls ( which could be a bad thing ) in the compulsories.
Handstand, handstand, handstand. Since PB and rings require a lot of handstand hold movements and of course they have to go through handstand for tumbling and giants.
Handstand on wall. Handstand on floor. Handstand on parallettes. Handstand presses or their variants.
They also need to develop a lot of lever strength. This can be done by training front levers on a pullup bar and back lever ( starting off with skin the cats ).
And of course with boys at that age, it has to be fun and not work. Boys love challenging themselves and other boys.
Crunches are lame. Start doing leg lifts progressing to hanging leg lifts and V-ups ( starting with tuck first ).
Also boys have to train a lot more static strength positions than girls because of their routines on the events. Lots of L sits, levers, that eventually turns into press to HS on rings, cross, strength to strength holds.