For example, 2 person fixed step pushing hands, various Ta Lu sets, 2 person weapons forms and
what John Kells called the "Dance".
The Dance is a 2 person fighting set. Perhaps this is a misnomer as it not fighting. What is teaches is timing, footwork, coordination, sticking, yielding, counter to counter and above all else, Spirit.
A frequent criticism is that it is a just a nicely choreographed sequence and sometimes this is not without foundation as people meander through it. However if you practise and investigate thoroughly, for example, how far is an attack welcomed in before you have to move, you can begin to see the value of this training. This type of fighting set also contains many applications from the solo forms.
I don't practise it much nowadays but I thought I would see what I looked like ( Vain but useful for feedback!). Unfortunately the battery on my camera ran out but there is enough footage to give you an idea. This is me doing it solo.