SQL> create table t (id integer, val varchar2(100))
  2  partition by range (id)
  3  (partition p1 values less than (50),
  4  partition p2 values less than (maxvalue))
  5  /

Table created.

SQL> insert into t select level, 'A' from dual connect by level <= 100;

100 rows created.

SQL> commit;

Commit complete.

SQL> alter table t move partition p1 tablespace ts_16k;
alter table t move partition p1 tablespace ts_16k
                                           *
ERROR at line 1:
ORA-14520: Tablespace TS_16K block size [16384] does not match existing object block size [8192]

ORA-14520: Tablespace %s block size [%s] does not match existing object block size [%s]
 *Cause: A DDL statement was issued that would require a tablespace of a
         block size different from the block size of the specified
         partitioned object to be assigned either:
           (1) As the object's default tablespace (or one of the
               object's partition-level default tablespaces,
               if composite partitioning is being used)   OR
           (2) To one of the object's partitions/subpartitions.
 *Action: Specify a tablespace of the same block size as the partitioned
          object.