Keep in mind that Raphael is one of only two archangels to not receive ult evos yet. I wouldn't write him off until you see what he gets.
Inevitably, it will be Healer, tbh.
What I just now realized is not only does Raphael work as an elemental slime when used right,
he's stackable with them as well.
Consider:
Siegfried/Cu Chulainn/Valkyrie
Kraken/Griffin/Unicorn
Something with row enhances: Berry/Melon/Lemon Dragon, perhaps?
Light Dominion Raphael
King Bubblie/Woodsie/Shynee
Siegfried/Cu Chulainn/Valkyrie
Now you have a workable mono-color mono-type team. Each of those three comes with x3 type attack leader skills, so that's an automatic x9 on at least four members of the party.
And then you have the respective slime: That makes x27.
And then you have a fully enhanced board thanks to Kraken/Griffin/Unicorn. That's another x2.80. That is a GRAND TOTAL OF x75.60 DAMAGE. No bullshit, no orb matching, no combos needed. And THEN you have any skyfalls that comes from clearing a full board. Tack even more damage on.
Ideally, if Raph gets a healer ult, the Valk team would be the way to go because that means Raphael himself gets in on the multiplied damage. That, and every member of the team aside from the suggested Lemon Dragon would be a Healer.
Oh, also: These teams are 100% farmable aside from Raphael himself (fruit dragons will have a special one-time dungeon in the future so you can get one of your choice).
Also also, if you want it to be even MORE ridiculous: use the special ults for Sieg or Cu Chulainn (or Metatron if you have her for a healer team). That's a x102.90 multiplier if you can pull it off. And that's STILL farmable, Metatron aside.
So yeah. Raph ain't useless, you just have to be creative.