The first New Alien unlocked in the series at the end of Book 1.

Jokingly referred to as the Second Uraraka by Class 1A, in reality this alien's no joke.

With the power to manipulate gravity to the point where it becomes telekinesis, This walking planetoid can alter weight the way Uraraka does, but with a major difference in that he's able to do it without having to touch what he alters. By creating invisible 'gravity wells' by flinging his power to certain areas, so he can manipulate objects, he also manipulates the density of certain points in the air, planet, and even space itself in order to alter the force of gravity.

To top it off, Gravattack's core possesses immense density, granting him his own gravitational pull that he can freely turn on and off and manipulate to no end. However, one must be careful as destroying Gravattack's core could theoretically (according to Nezu and Number 13) create a miniature black hole.

https://www.deviantart.com/misakalovesyou/art/MHA-Rise-of-Ben-10-Gravattack-865453952