Are we allowed to participate in the non-Islamic parties in the West such as- Republican and Democratic?? And are we allowed to form an Islamic political party here in the west? Jazakum Allahu Khairan.

All praise be to Allah, and may his peace and blessings be on the last and best prophet and messenger, Muhammad. In general, yes you are if that will bring benefits to the Muslims and their communities and the other communities as well. The details of which party to participate in or vote for must be left to the scholars and experts of the respective countries and the public should follow their scholars and experts. Allah knows best.