Teradata is a parallel database that is very similar to DB2 DPF (data partitioning feature) which has recently been renamed to IBM InfoSphere Warehouse (since parallel databases are most often used in data warehouse applications). It was previously known as DB2 EEE and still referred to that is some job ads.
If you search job openings for Teradata vs DB2 DPF (or EEE or InfoSphere Warehouse) I think there are more jobs for the DB2 parallel database than Teradata, at least in the US (don't know about India). But right now is probably not the best time to judge (by looking at job ads) what future demand will be for these skills.
Parallel database is a little more complicated than regular DBA work, so most people who learn DB2 DPF are already skilled in regular DB2.
M. A. Feldman
IBM Certified DBA on DB2 for Linux, UNIX, and Windows
IBM Certified DBA on DB2 for z/OS and OS/390