Answered: Pushing Many Cones with Flat Surface

SG9 limits possession to 1 cone

and possession is defined as

On the one hand, an intent is to prevent robots from hoarding cones by pushing them, but on the other hand, pushing/plowing cones with a non-concave surface is not possession.

Is it legal to intentionally push multiple cones with a flat (non-concave) surface in order to move the cones around the field (not merely to push them out of the way)?

Please see this Q&A for further clarification on the difference between hoarding and pushing/plowing. Remember that it is at the discretion of the Head Referee to determine whether hoarding is occurring or not. To do so, they will take into account things like the context of the full match, whether or not the action in question was Match Affecting, if the team in question had been warned about this situation previously, etc.

This topic will be one of the subjects of the referee training videos later this year, so keep an eye out for those when the time draws closer.