Lol what? Ostheer can spam call-ins?
The only time I can conceivably spam any sort of off-map is with CAS or deliberate construction of muni caches. In that case, Stuka CAS from Lightning War, Blitzkrieg, or Jaeger Infantry is the go-to spam, but that happens in rare cases.
Also, as a note, *Wehrmacht
Finally, everything suggested here would work to counter blobs. MGs, Pack Howitzer, Centaur, Mines/Demo, etc.
I don't know what your rank is but, typically, as players get higher ranks, blobbing is encountered less often in 1v1s and 2v2s the closer one's rank gets to 1.
Have to call 2 players out for you. CaptainSprice and Paul.a.D