If the server doesn't have GregTech and the client does, connection to the server will be refused, much like with updating mods server side only.
There is enough info about GregTech its config files on the internet found
here.
The electric tools i cant recall how i changed them, but in the end it was a hassle to do so, i ended up changing back the following settings files:
Recipes.cfg - usefullrecipes\ic2recipes\circuitry = everything below those markers i set to false basically (not sure if ic2recipes are needed as there only for Qsuit stuff)
GregTech.cfg - features = contains some optional settings you might want to change like the Forestry bronze nerf, although im not 100% of its use, it contained the words nerf so i set it to false.
GregTech.cfg - machines = Also optional, but these are setting added by Gregtech, for vanilla experience you might to change these, i did for now but this is a setting i was tempted to not change since they actually make sense to me unlike some other settings.
GregTech.cfg - unificatortargets = this one is acually usefull, i set the all to true to reduce the number of conflicts between items that have been added by a few mods, if you want a clear explanation plz use the link i posted above to review these changes.
And that is all i changed basicly, with the unificatortargets and usefullrecipes\ic2recipes\circuitry being the most important to undo all the GregTech recipe settings and unify most resources (that gregtech uses).
I did pinpoint what kept the wrench and stuff on gregtech settings before, but as i failed to save my config a few times while updating i simply use the method mentioned above to change it all back to Easy mode and dint bother to figure that out again.
To test before posting i installed the Ultimate pack, copyed over these settings files i changed from the Mindcrack Pack, and now i have a Ultimate pack on Gregtech easy mode including the wrench (test for especially for the wrench as i was unsure about that one)
Although if the server is owned by friend i would just still ask them to zip/rar the config folder if you want your single player to be 100% the same as the server they run.
Gl hope this helps.