Is there anything you would have added or changed to how Terastalization worked?

Personally I would have added to restriction that pokemon could only terastalize into types that they had a corresponding attacking move of and done away with terablast.

Another idea is give certain pokemon a bonus if they terastalized into a specific type to make the 3-4 best typings the obvious choice. Like a grass tera type Sudowoodo retained it's rock-type resistances, etc.