heh here's a HOPEFULLY clear answer. I've done this, so here we are.
I ran my Voodoo 3 2K AGP on my Windows 95 system. It ran FINE, but windows didn't think it was an AGP slot. the AGP slot has some sort of PCI to PCI bridge if I remember correctly, and Windows saw this device, which then showed up in the Device manager as a conflicting device. Don't worry, it really isn't conflicting, Windows 95 is too stupid (rather old) to figure out what to do with it.
this was with OSR2.5, with ALL the upgrades. USB Supplement too (which BTW didn't let me use my USB Steering wheel, but it's goin fine with Windows 98 right now).
So, I imagine that all cards that don't really use the special feature that AGP does (namely, the different way of accessing data from the memory, and now you could consider Sidebanding and Fast Writes an AGP feature) offer, will run in Windows 95 just fine. With cards that actually impliment it, (TNT 1 and 2, Riva 128 I think did too, and of course the Geforce 1 and 2) I suspect you MIGHT need to go Windows 98, though AFAIK, the Riva 128 was available before Windows 98.. hmm. I don't remember.