If every line has same number of fields then you can do:
awk '
{
for(i=2;i<=NF;i++)
rec[i]=(rec[i]?rec[i]RS$i:$i)
}
END {
for(i=2;i<=NF;i++) print rec[i]
}' file
If the number of fields are uneven, then you need to remember which line has the maximum number of fields.
awk '
{
for(i=2;i<=NF;i++) {
rec[i]=(rec[i]?rec[i]RS$i:$i)
}
num=(num>NF?num:NF)
}
END {
for(i=2;i<=num;i++) print rec[i]
}' file
Output:
b
b1
b2
b3
c
c1
c2
c3
d
d1
d2
d3