Leave a Sepctrobe in the Incubator for awhile. You will begin to see blue dots flying over it. Tap on it to evolve it.

To shorten the time it takes to make a Spectrobe evolve, put it in the Incubator and pet it with your stylus.

If you do not want to wait the amount of time needed for a Spectrobe to evolve, put the Spectrobe in the incubator, save the game, then turn the Nintendo DS off. Turn it back on and chose "Settings" at DS system main menu, then change the time forwards however long is needed. Resume the game, evolve the creature, and take it out of incubator. You can then set the time back to the correct value if desired.