Get a mob and rename it to [Any_Name_You_want] Make sure the name doesn't have spaces or the command wont work. Once the mob is spawn and ready to
go (So it has things you want on it likes saddles etc) Then paste in the following command /tp @e[name=[Any_Name_You_Want]] [Your User name] (For example: /tp @e[name=Bob] teabag300. When you have done this INSIDE A COMMAND BLOCK put it on repeat (The Purple Command block) and put a red stone torch next to it! Your done!
Also if in the chat it says the command in italics then use the command /gamerule commandBlockOutput false