Default character animations allowing for custom skins

Im looking for help on Creating and rigging a character with all the animations i need for my game. The character will be box like similar to minecraft but more "Chibi"

I want to be able to have players create ingame their avatar skins that can bee seen via multiplayer or they could be imported assuming they meet the required dimensions and format.

So.

I feel like this will save me a lot of time back end wise instead of creating sprites for every item/weapon/gear/character.. and instead... create one "blank" character model and let them import their own skins that would all use the same walking animations ect..

how can i do this and could anyone point me to a tutorial that could help get me started on this?