Hmm... Pamela's a project character. There's certainly things you could do with her though. Another possible candidate for Firefly, of course. Though not great until she gets Physical Immunity. She -does- at least get auto-life!
Option 1: If you really want Mana Khemia characters to retain some switch flavor, you could try implementing a universal Switch-in command for other PCs, and letting the player decide whether Pamela starts on the field or in reserve, forcing a choice between a party of 5 or a party of 4 with a reserve slot. The first thing that comes to mind with this is something like Jude (or any fast PC) gets a turn, attacks and switches in Pamela, she gets to activate her switching-in ability, then has to wait for her regular turn. And as the MK character, she's the only one who could allow Jude to switch back in. Otherwise, he's stuck in reserve til the end of the match (functionally KO'd if everyone else on the team dies).
It would probably have some interesting tanking uses, but it wouldn't be a particularly strong strategy as it removes an immediately-useful warm body from the party, but conceivably it could increase overall damage over time.
Option 2: Having two MK characters (Nikki, Roxis, Anna, Jessica all translate well for various niches). Limiting Switch to only working when you have 2 MK characters in your party. Less interesting, but functionally the same in most respects assuming you allow a reserve slot.
If this is the only palatable option, then I would suggest implementing a Nall-style pricing option. For example, Pamela (1.5) is normal, Pamela (2.0) would be "Pamela in Reserve, doesn't use up a party slot, can only switch in if another MK character is chosen". The extra 0.5 cost should cover the utility that Switch allows to a party.
Thoughts?