>>23232432The Dratini has been shown with both of those personalities, from a benevolent controller of rain and storms, and a monster with the largest attack stat in Gen 1 with two signature attacks based around its rage.
There's also the aspect of the line of growing a horn, the crown of its losing its lesser dragon status.
As well as the trial aspect, by making Dragonair need so much experience to evolve again. To this day, Dragonair is still one of the highest caps, only to be beaten by pokemon from a generation where so many final evolutions happen at high levels.