Much thanks to boko-kun for his excellent Pip/Tumalu guide, which provided the information you see here.
Pip has the ability to transform into different forms based on the Elements used in battle. If you use Dark elements (Black, Yellow, Red) he'll lean towards a Devil form (more physically-oriented). If you use Light elements (White, Green, Blue) he'll lean towards an Angel form (more magically-oriented). There are a total of five new forms he can change into (the first two are the first evolution, the last three are his final forms):
Light: Pip grows wings and turns pink.
Dark: Pip grows small horns and turns purplish.
Light then Dark or Dark then Light: Pip has horns plus butterfly wings.
Light then Light: Pip grows angel wings.
Dark then Dark: Pip grows devil horns and turns purple.
For the first evolution, Pip's stats will change (all stats will raise, but physical stats will raise more for the Devil form and magical stats for the Angel form). In his final evolution, Pip's stats will raise yet again, plus his Element grid will grow, allowing him use of a L. 7 technique. Each of the final three forms has a different L. 7 tech, as follows:
Light-Dark or Dark-Light (One enemy): "CanonCannon". Pip becomes a human (or monster) cannonball.
Light-Light (One enemy): "Heaven'sCall". Pip strikes the enemy with holy magic.
Dark-Dark (One enemy): "Hell'sFury". Pip goes nuts and attacks several times.
Here's how to get Pip to change. He needs a certain amount of "points" to evolve. Split the Element colors up into two "teams", Light and Dark. If Pip uses an Element during battle, that Element's team gains 2 points; if a party member uses an Element, that Element's team gains 1 point. The points remain even if Pip dies or the party runs away. Once Pip evolves, all points reset.
To get to:
|Form||Light||Dark||Light-Dark or Dark-Light||Light-Light or Dark-Dark|
|You need:||100 pts.||125 pts.||200 pts.||300 pts.|
Here are the Element grids for the final three forms:
Dark-Light or Light-Dark: 7 6 6 5 5 5 3 2
Light-Light: 6 6 6 6 6 6 4 4
Dark-Dark: 8 8 6 6 4 3 2 2
Two more things: The single Element which Pip uses the most during battle will become Pip's new innate element when he evolves. And: Pip's stats will NOT raise until you get a Star, so if you already have all 99 of them, you're out of luck.