Hades adds the missing A frame atk down and a ton of other debuffs (especially when awakened) to reduce damage. For Satan and Thanatos, one of the most important aspects are the def down debuffs, but since -50% is the debuff cap, having both of them is kinda overkill (at least with the 20% of dark amaterasu). If you want to go full glass cannon, you can probably substitute Hades with Satan/Thanatos + Arthur + Provisional Forest, but usually you'll want a more balanced team.
For example you could run Shingen + ambush with Satan or Thanatos, Dark Ama, Hades and Osiris for -50% def and -40% atk (-50% with an eidolon summon).
The next dark eidolon will be medusa in about 2 weeks (who's rather bad, but better than nothing). The next good one won't be coming until end of august/early september. Even the eidolon shop might be out before that, which would allow you to trade in Jack or Amphisbaena.