Colloquially reasonable, but not enough for profiles imo.
We need evidence that they use energy to create or prevent the destruction of a large mass, and that they use more energy in dishing out physical attacks. Them being created of (presumably, if we don't believe that creating Fountains within Fountains changes things too much) an amount of energy which could also create a large mass is nice, but scaling that full energy to attacks is missing substance, I think.
The thing is not much due to the lack of feats, but more the nature of Darkness itself.
Jevil could warp his cell, and that disappears once he's defeated, Spamton NEO can warp and manipulate the city he created in the Mansion, with that disappearing at defeat as well (yes I am gunning for 7-B Spamton NEO now, I was inintially against it but the new context from the Titans made me change my mind on it), and given that Spamton and Jevil are both Darkners, I can see the fact that Darkness is something that the Darkner can use to create/manipulate a place at will, with that disappearing at defeat (AKA Jevil becoming too tired to keep fighting and Spamton NEO's wire thing in the Pacifist ends).
"But what about the common enemies being 7-B then!" yeah 7-B is not an absurd jump compared to 4-A tbh.
Ehh, pretty sure Ralsei said "Jump on it, it won't attack itself", not "Jump on it, get away from the darkness". That specific approach seemed (at least initially) fuelled by wanting to not be attacked, rather than by outrunning the darkness.
And that doesn't really invalidate the offensive troubles they had.
Because being attacked would mean they'll get slowed enough to be engulfed from that. Plus Ralsei has a clear inferiority complex as he does not seem to be worthy of even having his own room at Castle Town (he literally sleeps in a room without ANYTHING, not even lighting), so him underestimating himself is not that far fetched. While off-topic, we did remove from Monika the whole "she's bad at coding" from her weaknesses because of that being just a reflection of her own self-hatred when facts speak otherwise, so I think the same applies here.
There was still the typical gameplay scaling, but yeah, nothing in cutscenes.
I meant cutscenes there ye. For example Palkia being OHKO by a wild Druddigon is just a game mechanic due to it just how the game works rather than a reflection of the lore, but if the thing is heavily scripted to make it happen in the actual story progression and/or happens in a cutscene, then that's clearly intended to happen in the actual story.
Chapters 1-3 had these while 4 didn't, so we can go more lax around it, ye.