I feel like the author might be legitimately confused about his own character. The style that Agito and Lu Tian are using and that's being called "formless" is technically a formless style, but Agito shouldn't be using it and Lu Tian shouldn't be able to- this isn't the general formless technique, but instead the custom-made anti-Gaolang martial art improvised by Agito in the Kengan Annihilation Tournament, complete with a low grappler's stance and shoulder movemenets for "curbing the end" of a boxer's blow. This stance was used vs Gaolang, but not against Kuroki or Okubo when Agito used Formless against them.
I suggested earlier that the author might be legitimately mistaken about the nature of Formless, but I don't actually believe that. Sandrovich seems to be very organized, and there's no way he didn't reread his own chapters for visual reference. On the contrary, I think he decided to use the anti-Gaolang martial art as a visual style to make the Formless stance immediately recognizable- important for a mirror match like this.