This is a very open-ended question the way you asked it.
I teach a lot of partner workouts, as well as partner drills within larger group classes.
The key, IMO, is to be able to pick exercises that can be done no matter who gets partnered with who in your class. So if you have two partners who are equal in fitness level and height, you don’t have to worry so much about multiple options as you would if you’re teaching 4 people (in two pairs) and they have wide differences in weight and strength.
I typically alternate between exercises that are done in parallel – each person doing the same exercise but at their own pace – and as a pair like a partner core drill, a shadow drill, a Buddy System exercise (equipment meant for 2 people). When I’m teaching 4 people, I alternate partners so that everyone partners with everyone else.
When I have partners with very different strength or weight, I tend to pick partner exercises where I can manipulate the base of support. If an exercise is “easy” or a person is “strong” relative to their partner, I can make them stand with their feet closer together, or on one foot. That way, a deconditioned beginner can train alongside one of my long-time regulars, I just give the beginner the advantage of leverage and reduce it from the regular and both get an appropriate challenge.