GHEIST is pretty good in T1 DT. I always usually reach rank 4-20 when using my Gheist cards.
As for Skeelz tho, I think for you to reach the higher ranks, you'll have to use the really good cards (tho it's been a while since I myself have used Skeelz in T1 DT).
For some suggestions:
5* - Michael, Goure, Tomas
4* - Dr Falkenstein, Greem Cr, Xingshu, Miss Xingshu
3* - Arantxa, Andy Ld, Chiara Cr, Plunk, Sandro, Henry
2* - Yomi Ld, Redra, Sasha, Caroline