PS2 3V uses a 4 Ohm speaker.
PS2 5V (older with the 9V battery) used 16 Ohms
PS1 uses 8 Ohms
Also, should say, measuring just Ohms is not enough to determine good speaker vs bad. Since a speaker does have to move and move freely- it takes multiple tests- yes, basic resistance, across the coil, but also check for coil to metal frame short, and last, even a bad speaker that is jammed and won't make much if any sound- could test OK electrically.