Here is my quick take on a Shapeshifting Druid like Class.
Requirements: Miracles Campaign Quality, Alignment, Survival 6+, Pathfinder Basics
Class Skills: Athletics, Crafting, Impress, Medicine, Notice, Resolve, Ride, Survival, Alignment Skills
Skill Points: 8 + Int modifier per level
Vitality: 6+ Con modifier per level
One with Nature: You gain a companion as per the Animal Partner Feat. You may gain the Animal Partner feat a second time later, as your character options allows. Also you gain a 20% discount on Weapons & Armour that are constructed from natural plants only. (Ie contain NO metal).
Wildshape I: At Level 1, you gain the Shapeshifter I NPC quality with one chosen Animal form with an XP cost not to exceed 30 + 5 x your class level. At the start of each adventure you may assign your chosen forms. During the adventure you may spend 4 hours of Downtime to study another animal and change one of your chosen forms.Further, you remain in your chosen form until your change form or until the end of the current scene.
Wildshape II: At level 3, you may choose another Animal form which you can take (for a total of 2 forms). Further when you use your Wildshape ability you heal naturally as if you had rested for a number of hours equal to your class level.
Wildshape III: At Level 5, you gain the Shapeshifter II NPC quality. This replaces your previous Shapeshifter quality.
Wildshape IV: At level 7, you may choose another Animal form which you can take (for a total of 3 forms). Further it only takes you 1 Full Action to assume a chosen form.
Wildshape V: At level 9, you may choose two more Animal forms which you can take (for a total of 5 forms).
Nature Sense I: At Level 2, you may substitute your Survival Skill in place of your Saving throw against spells from Charm Discipline . Further you gain Pathfinder Mastery Feat.
Nature Sense II: At Level 7.you may substitute your Survival Skill in place of your Saving Throw against spells from Illusion Discipline. Further you gain Pathfinder Supremacy Feat
Way of the Wilds: At Levels 4,6, and 8, you may either gain 1 Terraint feat or take 1 step on one of your Alignment’s Path.
Venom Immunity: At Level 4, you gain Damage Immunity (Contagions) NPC Quality.
Truly Wild At Level 8, you may use your Wildshape abiilty to shapechange into chosen forms with the Plant or Beast type.
Timeless Body: At Level 10, you no longer feel suffer from the ravages of time.
Until killed, you appear to be an age of your choosing up to your actual age. This age must be chosen when you gain this ability. Further, your Intelligence, Wisdom, and Charisma scores all increase by 2 each.
Table XX: The Wilder
Lvl BAB Fort Ref Will Def Init LS Lgnd Abilities
1 +0 +2 +1 +1 +1 +1 +0 +1 One with Nature, Wildshape I
2 +1 +3 +2 +2 +1 +1 +0 +1 Nature Sense I
3 +2 +3 +2 +2 +2 +2 +1 +2 Wildshape II
4 +3 +4 +2 +2 +2 +2 +1 +2 Venom Immunity, Way of the wilds
5 +3 +4 +3 +3 +3 +3 +1 +3 Wildshape III
6 +4 +5 +3 +3 +4 +4 +2 +3 Way of the wild
7 +5 +5 +4 +4 +4 +4 +2 +4 Nature Sense II, Wildshape IV
8 +6 +6 +4 +4 +5 +5 +2 +4 Truly wild, Way of the Wilds
9 +6 +6 +4 +4 +5 +5 +3 +5 Wildshape V
10 +7 +7 +5 +5 +6 +6 +3 +5 Timeless Body
I'm not quite sure on the Gamebreaker and I need to say something about being able to change your chosen forms in downtime or soemthing.
Edit: Added in some info about duration of Wildshape and changed the gamebreaker and add a new ability to include different forms.
Edit II: Reworked Gamebreaker and added a bit more to Wildshape.