A monster is a creature created to destroy Mech-X4 and the team, but it's especially created to destroy Ryan Walker, the pilot of the robot. Monsters have been featured in every episode since the first, and they will continue to do so in Season 2.
Seth was waiting for Grace to come in the monster.
The monster could have almost defeated Mech-X4 if they didn't leave.
When Ryan was going to get the Primorphous Core missile, Seth got into his monster to get it first.
Ryan got the Primorphous Core missile before Seth and Ryan threw the missile back at Seth.
Seth evacuated by ejecting out of the monster.
Traeger's Monster Form uses a similar design with recoloring and some modifications, before getting a completely new design in Versus The Zero Gravity.
In Let's End This! Part Two, she was in Mech-X4 and she talked to Ryan and Mark about them being the pilots of Mech-X4. She rejected them and went to Seth in the monster.
When Grace tried to fight the monster in her brain, she was in the Med Bay sleeping. Leo was watching her so she doesn't see where she was.
After she woke up, she didn't remember having a monster inside her brain.
In Versus The Outbreak, Grey tested the ooze Seth made that would turn East Bay City High to monsters. She mixed the ooze with the chocolate the dinner lady was making.
It doesn't work and they were just after the remaining students who weren't infected.
Its weakness was freezing cold. The Mech-X4 team used Mech-X4's Cold Cannon to blast the students with the freezing cold.
In Let's Get the Big Bad!, Grey fell into Clawboon's ooze which was zapped by the X-Weapon.
In Versus The New Evil, it was revealed that Grey could turn into Clawboon whenever she wanted.
Kangarat
Armadillo like bat
Squid like tortoise
Creating Monsters[]
Primorphous Gel is a source for creating monsters. There are different checkpoints where a pile of Primorphous Gel can be found. If a Primorphous Core ("monster heart" by the Mech-X4 team) is inserted into the gel, it takes a couple of time before a monster can grow. However, if the monster is defeated, the monster turns back to Primorphous Gel ("monster ooze" by the Mech-X4 team) and the Primorphous Core dries out.
If the gel is zapped by the X-Weapon, a human could turn into a monster once they fall into the ooze.