Before all of the Frizzilians were destroyed they were incredibly destructive to reality and as a whole were powerful enough to take on omnipotent beings. They first began appearing when a mysterious universe blew into existence and disappeared. No one knows where this universe came from but some theorize its purpose was purely just to bring the Frizzilians into existence in order to take down the beings of omnipotence and then to destroy other universes. When the first Frizzilians appeared they did not immediately start attacking the the god beings, they interacted with other beings normally but mainly kept to themselves. There were many other instances of this mysterious universe appearing and disappearing only to bring more Frizzilians. Once their numbers were large enough they began their attack, which was the first multiversal war in existence. The gods were not prepared for this especially because of the amount of power the Frizzilians had as a whole. The gods however were successful in defeating them but it wasn't an easy success and there were many minor beings who did not survive and many universes were destroyed too. As of right now there is only one Frizzilian left in all of existence.
The Frizzilian creates pocket realities and tricks other beings into coming into them. Entering these pocket realities causes the beings to be completely subjected to its physics and logic the Frizzilian decides to implement within the reality. The Frizzilian does this in order to survive and further it's existence. As long as it has weak minded beings and is able to constantly contain them within the reality, the Frizzilian is immortal. The only way to leave the pocket reality is if the Frizzilian lets you go (which is unlikely), you kill it (pretty much impossible), or you give it what it wants until it is done with you.
The Last Frizzilian
After the war ended one Frizzilian escaped, and went to Earth to hide from the gods who were looking for any Frizzilian survivors. This one in particular was able to survive because it was the most powerful of its species. This Frizzilian then disguised itself as a female school teacher that went by the name of Miss Frizzle and began plotting the next multiverse war while it trapped the children of its classes within its reality and used their energy to live longer and to summon the universe that created it in the first place.The Frizzilian decided to keep the children entertained so they wouldn't suspect a thing and created the 'Magic School bus' and took them to various places. These trips would only take place within Frizzle's reality which is why impossible things are able to be done.
More info will be added in the future