I would think a hot-spring would be Water/Fire type, which could work well with that design because of the steam eyebrows and the tortoise aspect. However I don't think it should be legendary, maybe just really strong and only able to be encountered like once or twice, like Snorlax or Rotom. If it's part Fire, then I would suggest the head, neck, and legs be light orange and the beak, eyelids, and collar around the neck/shell be either a darker orange/red or be lighter yellow. The steam could be light blue or grey, and the shell could be turquoise (darker and greener for the main shell, lighter and blue for the spots).
Also another idea for a Pokemon could be based off of Dolly the Sheep (the first successfully cloned sheep). Apparently Nintendo was planning on making a Pokemon based off of her (http://bulbanews.bulbagarden.net/wiki/Un..._interview), but decided against it due to controversy. But being a fan project, we don't really have to abide by any rules.
Also another idea for a Pokemon could be based off of Dolly the Sheep (the first successfully cloned sheep). Apparently Nintendo was planning on making a Pokemon based off of her (http://bulbanews.bulbagarden.net/wiki/Un..._interview), but decided against it due to controversy. But being a fan project, we don't really have to abide by any rules.