What is the largest planet size that can be pushed out of orbit?

This is a spin off from this question here.

I want a spaceship or several spaceships to be able to move a planet out of its orbit around another planet. How big could the planet realistically be before it becomes an unrealistic or impossible task or before the forces involved have a detrimental impact on other planets / spaceships in the vicinity?

Assume we are 300-500 years into the future and consider the resources that could have been developed / perfected by then. Please state if there is any other information you require.

EDIT - some clarification:

The planet / moon needs to be moved out of it's orbit and become free-moving in space, ie not in orbit around another planet or star or planet. Allow maybe 200 years maximum for the process to be carried out.

posted over 7 years ago

5Diraptor‭

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