Granted, it gains enough mas to be considered a planet again, this changes its orbit, however the extra mass changes its orbit enough and now its on course to crash with the sun.
On its way there, its gravity has various negative effects on the entire solar system, including other planet's orbits and their moons.
Some moons leave the planet's orbit and other crash into their planets, Earth's moon somehow ends crashing on Mars, tossing it out of orbit and close to crashing Earth, barely avoiding collision, but having major impact on the sea and causing major damage.
(I'm trying to make my answers a bit longer, just for fun, and practice.
)
I wish I could come up with better twists to wishes.