Is there no superpet trope? Pokemon/Digimon/httyd/transformers even

I watched how to train your dragon and I realized, that what made me love it most was the parallels it had to digimon in that a boy gets this extremely powerful friend who is tied to him. Tied by love and some external thing like an artificial tail, a digivice or a pokeball.

I have a lot of thoughts on this, but much rather I would like to get more from reading this site. How can this not be a trope when digimon and pokemon and probably 15 others shows that are exactly like that exist?

Please use Lost And Found (aka Trope Finder) for these types of inquiries. For reference, the trope you're looking for is A Boy and His X.