Board Thread:General Discussion/@comment-4435241-20170524111014/@comment-31337598-20170626082434

Tsunami in Season Two ( which is in the same timeline of Ares ) was Third Year and not a High School Student,

Tsunami was in High School only in the Time Skip between episode 125 and 126-127

Source : http://inazuma-eleven.wikia.com/wiki/Legend_3_Nensei

As you observe, the team contain players in their 3rd Year in season 2 and 3,

Teres, Tsunami, Edgar, Desarm and Sugimori