Per the service manual:

Tools Required

The following tools are required to disassemble a PowerBook Duo 2300c system:

• T-6 torx driver

• T-8 torx driver

• T-10 torx driver

• IC extractor

• Jeweler’s flat-blade screwdriver

• # 00 Phillips screwdriver

• Duo battery contact alignment tool

That said, I've only needed the T-8 and a Philips and I've done complete tear downs. The bigger or littler torxi may be needed for disassembling the screen, which I haven't done. (I just tore down my 5300ce for a MV16-EM. The T-8 & Phillips were, again, all I needed.)

I was going to point you to the PRAM batteries that have been on eBay since I first searched Powerbook Duo a year ago, but they are gone...