Is there a major arc in dragon ball (z and onwards) with no new forms introduced?
Just occurred to me that there might not be one
Saiyan saga has kaioken which isn't technically a form but may as well be
Frieza saga has super Saiyan, cell saga has super Saiyan grades and super Saiyan 2, buu has super Saiyan 3, bog has god, then blue, blue evolved and ui
GT only has one new transformation and several arcs. In Super, I believe there is no new transformation in the first tournament arc? Unless you count the combination of Kaioken and Blue.
That's a fair opinion to have since I believe even Toriyama said as much. However, in the end there is no such thing as a true canon - with the manga, anime and movies there are 3 different canons for Super alone. And personally speaking, they all suck just as much as GT did except for a few of the movies.
No that's true actually, wouldn't really count blue kaioken as a new form as it's just a new way of using existing stuff though again serves the same purpose to the story
Haven't seen GT yet so couldn't comment there though ssj4 is absolutely the coolest looking transformation