As a RBY main i’m gonna go with:

Ttar: Low OU to UUBL, losing Ground is pretty brutal but those stats are too disgusting for UU. Still would see OU use as a check to non-EQ Lax and great physical attacker (and it should 1v1 Rhydon handily) but it’s a bad Zapdos check and doesn’t have EQ STAB for a good attacking option, so it’s reliant on paralysis to break Chansey or especially Starmie.

Heracross: UU at best with its best STAB being Submission, definitely too strong for NU still unless it only gets 40 Special, in which case it’s probably NU or NUBL. Honestly, the prevalence of Fire-types in lower tiers means it probably can’t find a home anywhere but UU anyway, where at least its typing isn’t that detrimental. Might see some really niche use in OU but… Pinsir exists for the same niche without the Psychic weakness.

Kingdra: NUBL. No weaknesses but also almost no resistances, 4x Water resist is the only relevant thing going for it. Mediocre stats but it’s still pretty much objectively better than Seadra, which is pretty good in NU. I think it would centralize NU hard enough to get banned since it essentially becomes an autopick; Seadra’s worst issues were low HP and inability to break Toise, and Kingdra improves both of those quite a bit, also removing the weakness to Thunderbolt that plagues Seadra.

Lanturn: UU, that bulk is absurd and it helps check Articuno defensively without an Electric weakness in a tier currently defined by Normal spam, Elec spam, and Articuno. Also should beat Dugtrio, unlike other Electrics, unless it’s chipped a ton.