You can use a pan on a griddle and I have done it before myself when my stove top went out and needed to cook some food in a pan.
Although it will take a bit longer for the pan to heat up to enough temperature to begin cooking the food the pan on the griddle will work just fine.
However cooking in a pan on a griddle is not the best way to cook in a pan and I would recommend getting a small cheap hotplate from Walmart for around $10.00 if you do not have a stove and need to cook in a pot or pan as the hotplate will cook the food in the pot or pan much faster.
But you can cook in the pot or pan on the griddle but it will just take a bit longer so you'll need to start cooking the food much sooner than you would with a stove or hotplate.