Suppose I'm using Dedenne and Gothitelle, and my opponent is using whimsicott and another Pokemon. Gothitelle uses magic coat, and whimsicott uses taunt on Dedenne. Will magic coat protect Dedenne and bounce the taunt onto whimsicott?
No, Magic Coat will not bounce the Taunt used on Dedenne back onto Whimsicott because Magic Coat only affects the Pokemon that used it.
Hope this helps!