Is the 12 volt battery in the passenger compartment of Toyota hybrid vehicles a regular lead acid battery or AGM?
Gen 4 (and PRIME) -just a regular. NOT AGM. But it's under the bonnet. I believe some of the old ones in PRIUS are in the boot - and are AGM - but wait till a Gen 2/3 owner chips in.
It is a good idea to spend a few extra bucks and GET an AGM replacement, regardless of what the OEM one was. The specific vehicle in question doesn't matter. AGM is better and lasts longer. But yes, any battery mounted in the passenger compartment needs to be a SEALED type, most often AGM.