Provided you use the same frequencies (which may be assigned to different channel numbers on different radios) you should be able to communicate with any other FRS/GMRS radio with one of the Motorola hybrid radios. I do it all the time between my Audiovox GMRS-1525 and Motorola Talkabout 250

FRS Channel 1 462.5625 MHz is suggested by some as the FRS calling channel. This is also one of the GMRS interstitial channels (between 462.550 and 462.575, hence the name). Even the simplest, earliest manufactured FRS radios with only 1 or 2 channels usually have this. Most handheld GMRS radios will have it as well.

In an emergency, you would want to disable any and all privacy codes (CTCSS/PL or DCS) and voice scrambling for maximum interoperability with other units. You would attempt to make contact on FRS channel 1 and then move to another channel if available.