fur just mirroring the animation left and right based on current position of the character you can try this C2 file, the last 3 condition events are for mirroring the animation, there are no plugins needed. however you might need the plugin to move ur character automatically unless u want to code it manually also.
And you can achieve that by giving the character u want to move in a loop a variable called moveto and set it to 1 or 2
and that would continuously move ur wanted character left and right, combined with the animation events from the capx above it should look pretty smooth without any plugins, but then you would use some extra events that you previously saved with the plugins/behaviors.