Dependencies are automatically managed using the metadata included in the functions. The error you get indicates that you are trying to install functions that require a higher version of some of the basic functions already present in your Eclipse installation - although Eclipse is very modular, and even several versions of the same function can coexist in one installation, this is not one of the main functions.
I assume that you are trying to install WTP for Galileo to exit in Ganymede. Or you have used your Eclipse installation for too long and installed too many features - this happens from time to time. Your best chance is to download the new Galileo release.
BTW: WTP (?) Ganymede, 3.4 , alredy