Let's see.. When you "transform" I assume you're actually getting rid of one character, and adding another, based on your information.

If this is true:

1) Ralf (the "secondary" character) is considered to be his own character, with his own permissions to items/growth rate/icon/battle char/etc.

If you want them to be similar (or completely the same) you'll need to make sure Ralf can use the right items through the Database and add whatever spells you want.

2) Since Rolf (the "primary" character) is out of the party and Ralf is in it, you won't get Rolf back automatically after any battle is complete.

You'll need a Common Event on Parallel Process, that removes Ralf and adds Rolf. It should be activated by a switch that you set when you "transform". (Parallel Process Common Events seem to only work outside of battle, so it's rather useful to remove Ralf inside one)

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If it's different than what I described, you'll have to explain further.