Hi Bala
1. For ECC validation purpose, you can find it in SAP Program for respectine transactions. You can take help on abaper for this.
2. For MDG validations please refer to How to Check or Derive an Attribute Value in MDG Using BRFPlus and Check and derivation rules
Have one logical question? Do you want to bypass ECC validations in MDG?
Basic behind this is all confiuration is done in backend ECc and used in MDG also.
So even if you try to bypass validation upto reviwer step (Possible in node Congigure properties for Change Request Step) CR give error at the time og activation of CR.
You can build add on validation in MDG but basic validations bulit in ECC are not suppoosed to be bypass.
Hope this clears.