Here is the full list of all 38 Ben 10 achievements.
Completely upgrade one alien
Achieve a combo of 50
Collect a Sumo Slammer card
Defeat 10 enemies with a single Ultimate Ability
Defeat 10 enemies as Ben
Finish the game
Completely upgrade all aliens
Collect half of the Sumo Slammer cards
Collect every Sumo Slammer card
Defeat Zombozo
Defeat Queen Bee
Destroy 5 objects with a thrown enemy
Complete “The City” in under 15 minutes
Complete ‘The Funhouse’ in under 15 minutes
Complete ‘The Scrapyard’ in under 15 minutes
Complete ‘The Hive’ in under 15 minutes
Complete ‘The Canyon’ in under 15 minutes
Complete ‘The Tornado’ in under 15 minutes
Achieve a combo of 100
Hit 5 enemies with a single rolling Tweedledee
Cause a chain reaction of 5 exploding Bumblebees
Reach the top of the Weatherhead Tower without falling off
Defeat Zombozo without taking damage
Defeat Queen Bee without taking damage
Defeat 3 enemies with a single Four Arms throw
Defeat 6 enemies with a single Cannonbolt roll
Defeat 3 enemies with a single use of Heatblast’s ability
Hit 5 different enemies with a single shot from Grey Matter
Defeat 5 enemies with a single use of Wildvine’s ability
Defeat a Pie Juggler before their pie hits the ground with XLR8’s ability
Dodge Weatherhead lightning, then hit the attacking enemy by using Upgrade’s ability
Hit 10 enemies with a single use of Diamondhead's ability
Defeat 3 enemies with a single use of Overflow’s ability
Stun a self-destructing Bumblebee with Stinkfly’s ability
Complete 30 Bonus Objectives
Defeat the Weatherhead Prime without taking damage
Defeat 2 enemies with a Weatherhead Drone
Defeat an enemy as each of the 10 aliens in one fight