Kashimo is genuinely a strong t3 contender
this might be long and im probably just repeating points already said in this sub
(Stats)
Base Kashimo went extreme-dif with JP hakari which in it of itself is a crazy feat since hakari is about equal to yuta and he only sustained minor injuries and never needed to use rct while hakari almost died multiple times ( ill get into that soon)
Against Sukuna kashimo faught post-gojo meguma and survived against incarnated Sukuna for a while (keep in mind that incarnation does not restore output)
ch 253 Sukuna (lowered output than kashimo's fight) blitzed maki (relative to yuta) and ch260-262 sukuna who is even lowered output and heavily damaged (7 bf, soul dismantled, and ss katana through the heart) still beats a yuta who is in gojo's body(who is obviously stronger than regular yuta)
All this puts base kashimo stats wise at or above the hh's and conformably a blitz tear over them in MBA
(wincons)
Outside of stats, kashimo nearly killed hakari multiple times with his discharge and staff, hakari only survived these because his jackpot's rct is fast enough to save him from these one shots, and sukuna needed to use incarnation to survive it too.
No one else in the verse (other than debatably modulo yuji) has rct fast enough to survive one of these to the head, and at worse someone like yuta could maybe heal from one to the body.
This gives kashimo the edge against people in the same tear like yuta, uraume, maki etc
(anti domain)
too many people say he gets domain diffed but they neglect hwb, kashimo being the strongest of the edo should have it (Reggie had it common)
it doesn't require constant hand sign usage to keep it active. we see this with Reggie against megumi where he let's go of the hand sign and its still active (side note: sukuna kept the hand sign because he needed to counter domain and JL) for an opponent with a domain he would just need to periodically use the hand sing to boost output.
This is more meme based but he could theoretically throw his staff outside of a domain and recall it to break through the barrier
(RCT)
against sukuna he gets half his hand cut off and throughout the fight he heals it, I say its rct because its shaded in the same way higoruma healed his arm and is not electrified the same way the rest of his hand
im sorry that i didn't go deeper, specially into his mba scaling and wincons, its almost 6 am and I don't remember much on those right now, im also sorry for any spelling mistakes and stuff (again its late ) correct me if I was wrong on anything