I started playing the game again, I almost only play Ossas or Fort.
When they switch to Diggy (or other flanks) to counter my Osass, I always switch to Fort to counter them.
Oh and to counter other Ossas I usually switch to Diggy myself.
If I need DMG but Ossas don't work, I just choose Gloria or Mark to completely destroy everyone.
The only healer I play is actually a Chemist. I don't know, but I rarely choose a healer, even if we don't have one, my Ossas has more impact than any healer.
We'll see how high I can get in a week or so, then we'll see you again!