Early on in a campaign I run my group freed a full grown Battle Hydra from poachers on Yavin 4. It was an epic battle as a Pathfinder was able to connect with the beast before setting it free from its cage and bindings and directed it to attack the poachers, destroying their encampment. As the Battle Hydra took to the skies to chase the fleeing remnants, the Pathfinder took the time before leaving the camp to search it's cage. Rolling two triumphs, I gave him a lone egg as big as he was. They took it in and been with them ever since. At one point we roleplayed it out that the egg hatched into a baby Hydra, he has been taking care of it for many sessions but hasn't brought it with him as he soon after got another silhouette 1 creature, a Dark Wolf from a Weequay.
This Pathfinder has now picked up Hermit and is closing on his 4th force rating. As we will be jumping ahead in time, from pre A New Hope to pre Empire Strikes Back, we have decided that this would be the perfect opportunity for his Battle Hydra to grow from its silhouette 1 to a 2 (it's mother was a 3) allowing it to be rode as a flying creature. With the rest of the group having their own vehicles (Xwing, Ywing, Jedi Starfighter, and a Freighter) this won't be too overpowered in the right setting.
I am familiar with stating out vehicles but after looking at similar S2 flying creatures I am lost for what is strong verse what is over powered. There are some things it will need, a poison tail attack, a linked bite attack, cortoise armor and of course the ability to be rode. He's already begun training it but will have the required time available in the time jump. I am looking at help in fleshing out this best to be able to strong and useful. It doesn't need to compete with the Starfighters. I'll provide the light to its wookie page for additional details.