Answer:
I can be simple or I can be complex. I can be found in this riddle or in everyday life. I can be shapes or even colors.
I come with a train and go with a train and the train doesn't need me but can't go without me.
Some try to hide, some try to cheat, but time will show we always will meet.
I can wake you up in the morning but I require no electricity or winding.
Die without me, never thank me. Walk right through me, never feel me. What am I?
The answer I give is yes, but what I mean is no. What was the question?