(2) According to the chart, it can be concluded that:

② Rotate △A2B2C2 90 clockwise around the O point.

③ Firstly, move △A2B2C2 by the distance of B2B 1 in the direction of B2B 1, and then rotate the triangle obtained by translation 90 clockwise around point B 1.

Can make △A2B2C2 coincide with △A 1B 1C 1,

So the answer is: ② ③.