Trying to move the wanderer will cause it to vanish from your sensors and appear elsewhere in the universe.
It is not possible to move Xannoron. Leaving any ground forces on the planet will allow the Xannor to take control of them and use them as their own, starting the next day. If you leave Xannoron with no ground forces, it will be relocated and guarded with fighters but only a minuscule number of ground forces the next day.
It is possible to move the mercenary base after it is captured, but the following day it will contain a complete group (150,000) of ground forces again if the number of ground forces is 0. If you place 5 ground forces or so on the planet, only a few hundred ground forces will appear the next day instead of a few hundred thousand. Every day 25,000,000 credits is restored on the planet and since the planet does not move, it can be recaptured easily after the first time. If you only place one ground force on the planet, a plague risks reducing that to 0, resulting in a full number of ground forces the next day instead of the reduced number.
If you do not have the ground forces available to capture the planet directly, watch the newspaper and knowing the productivity will allow you to capture it using plasma bolts. Using the spreadsheet at the beginning of this guide, you can calculate that 10 plasma bolts will destroy 100,000 ground forces and between 100,000 and 300,000 production. For a bit of a gamble, 11 plasma bolts will destroy 121,000 ground forces and between 121,000 production and 363,000 production. Firing off a single plasma bolt at the mercenary base or any other planet will reveal its current productivity but is not an accurate indicator of how close to either the minimum or the maximum production damage a larger number of plasma bolts will do. The default even production of ore, organics, and equipment would cause plasma bolts to do close to their maximum damage in production. Since plagues rarely leave planets with anything approaching even distribution, the gamble should pay off as seen below:
Before a plague occurs it is only safe to use five plasma bolts to reduce ground forces as six plasma bolts will destroy a recently created mercenary base planet. If another player has attacked the planet before, then even five plasma bolts may not be safe. The only safe method is to use just one plasma bolt and then after discovering that planets actual productivity, plugging the actual productivity number into the spreadsheet calculator under “plasma bolts needed / productivity max” and then firing one less.