Check this threads,the first one is about UMK3 videos(there's one video of MK2 combos too) of all kind of insane combos and damage,and the second one is about character specific guides,they are well explained with move properties and all that stuff:

UMK3 combo videos


UMK3 character guides

and here is a combo transcript for UMK3/MKTrilogy in great detail:

UMK3 combo transcript>UMK3 combo transcript

i hope this helps.

*Props to MKKungBroken,DreemerNJ,NinjaGrinder,Konqrr and all the people involved in the making of the above stuff*