if the boards move with weight, they are off the sub-floor. This could be buckling due to lack of expansion gapping, swelling due to addition of wood moisture after installation.
Or maybe the staples were too short?

Ah-ha, it is an unbalanced engineered. They act more like a solid, because of the thicker wear layer, compared to the ply layers thicknesses.

The staples being pulled out, is going to impede, trying to get it to go back down and top nailing, without pulling the boards completely.

We are not given enough data to make any real conclusions here.
here is the facts listed:
1. Over existing wood.
2. Basement below. Looks dry.
3. 8 to 10 boards buckling.
- Don't know where.. center of room, near walls, size of room?
4. Don't know sub-floor wood moisture content.
5. Don't know product wood moisture content.
6. don't know acclimation.
7. Stated 1/4" top layer. I've seen very few of these.... 1/4" thick surface may, or may not, be equal since we don't know the product or the number of ply's.
8. Don't know the wood moisture content upon installation or the board set measurements to make such a determination.
9. She did say she stopped mopping the floor and the boards went down a little...

What are other facts stated not included in this list?