That's really laughable .... Let's see how will it affect the Indian Subcontinent even if you are able to do this
a)South India will not be affected because Himalayas play very less to none role in monsoon in South India . The ITCZ will shift irrespective of tibetian plateau. and the role of orographic barrier is done by western Ghats.
same is the reaction .They are caused by SW monsoon winds.Western India is also poured upon by the SW monsoon winds.
b)only northern India and that too above the tropic of cancer will be affected which includes parts of Bihar and Up and to some extent west Bengal.(Most of the rains in orrisa and bengal is coastal phenomenon) and if you are thinking that you can stop rains altogether the sadly you are extremely mistaken rather this will decrease the rains by around 50% in some parts of northern plains.
and it's fairly easy to counter your plan
Step 1: India will move Indo-Australian tectonic plate to a bit downwards so that a new landmass is formed by this process and then fill over this landmass so that a new plateau is created
and then we'll double the size of himalayas to an average of 10000 mts .
#MonsoonJihad of CPC will be an epic fail .