No, it's blue on both modes with default colors. The antlers and marking are light blue when it's out of combat, in combat the markings and antlers turn cream colored and get the extra 'veins' in different colors. The red one is the alleged shiny version, but it may be a hoax.
Currently SR'ring my X game to get a good Xerneas, but every time I get a Modest one and it has 5 31 IV's it's 0 in Speed, HP or Sp. Att. QQ
-If- it pops up in shiny, or if the game freezes, then you could safely say if it's locked or not, but ain't gonna waste time with that, I quite like the normal one.