our main, andpotentially most expensive,issue will be the forks – as cbmotorsport says – if the steerer is cut too short for the new frame your fubarred.
The seat post and seat clamp are the obvious ones.
Bottom bracket could be an issue depends,(if you’re using ISIS or external type) on if you have/havn’t got the right number of spacers if needed. If you are using a square taper BB you may need a new one all together.
You could also have an issue wih the front mech, dependant on make – most these days come with spacers (or you can get them easy enough).
Theres also a slight possibility that the rear (or front for that matter) brake hose may be too short/long. Long’snot much of an issue other than asthetics .
Last but no means least, you’ll probably need new cable and outers.
My tip would also be to completely strip the bike and clean all parts thoroughly before transferring. It’s tempting to whip off the stem, bars brakes,shifters etc. as one unit and try to fit them straight over – it can be done but stripping and cleaning is the way to go.
And don’t forget to wedge something between the disc pads during assembly.