I have a flight from Praque to Dubai and from Dubai to India. 2 different flight companies and 4 hour for a transfer from terminal 2 to 1 in DXB airport. I have with my only my hand luggage. Is it enough time? What experience do you have?
If I remember it correctly (early 2016 info), T2 is where the low cost airlines fly to/from - including FlyDubai. Then it is (was) not connected directly to T1/T3 via walkways.
However it does have the airside transit (a shuttle bus) before passport control. It it not regular and seems to be tied to arriving flights. There is a visible holding area for transit when you're walking toward arrivals with a service desk nearby. You would then need to approach the service desk and ask; I assume they would handle that. 4hrs is plenty of time for that.
And if you want to get out (not recommended with 4hr layover unless you take taxi - there's no metro in T2, at least not back in 2016), you go through passport control and jump on a (free) shuttle bus which goes to T1/T3.
It is more than enough time.
Once you land in Terminal 2 and enter the building (you'll have to take a bus, if I recall correctly), go to the left towards transit and pass through the metal detectors.
You'll see a large circular information desk, followed by the main transit hall.
If you do not have a copy of your next flight's boarding pass, approach the information desk. They will probably then transfer you to the dnata services desk (dnata is a company that runs the airport operations - it is a division of Emirates).
From there, you'll get a boarding pass and directions for transfer to your next terminal, which will be on a bus.
You do not need any visas.