If you look at page 9 note #2 in the Vex Robotics In The Zone game manual it hints at a possible robotic design. This note states,“If a Robot is touching a Cone on a Mobile Goal, that Cone and any above it will not count as being Stacked.” I believe that Vex put this rule in the game manual in case a robot stacks cones and places them on the goal after it collects a few of them. This is a good strategy because it would save time by allowing the team to have more time dedicated to collecting cones rather then having to take a cone to the mobile goal and going to get another cone and repeating this process. This strategy is very similar to ones used in the Vex Robotics Championship for Skyrise. More supporting evidence that I found was Note 2 on page 17 of the rule book. This note states,“Stacked Cones do not count towards the Possession Limit.” I believe part of the reason why this note was included was to give the teams with this “carry cones and dump later” design a slight advantage. Vex anticipates this robot design and wants to make sure that teams can legally use it.
I don’t really get you - are you saying that a good strategy is to put the cones on top of each other first and then carry all the cones and stack onto the mobile goal at one go?
If this is the strategy, then I would suggest that you take a look at the definition of “stacked” 
Or are you suggesting that we should carry the mobile goal around as we collect cones?
Yes.
Cones are only counted as “stacked” if they are on a goal. Therefore, you can NOT collect several cones by placing them upon one another, then carrying them to a goal. The intent is to have teams figure out a way to pick up mobile goals and stack cones on them.
This has been discussed and clarified. Here’s an answer given two months ago:
https://vexforum.com/t/answered-further-clarification-of-stacked-involving-possession/41731/1
The Official Q&A, where that question was answered, is considered part of the game description. All teams should become familiar with it.