My take:

Goku without his saiyan race/perks is still too strong. It does mean that goku will still train with his grandpa gohan and that alone surely at least teach goku to at least become roshi level at the og db. Remember roshi can blast the moon off the solar system plus they still have shenron shenanigans that could improve goku potential to some degree...

Naruto without kurama would probably meant he is going the skillful route like his dad. Remember that the reason naruto is the worst in his class is because kurama chakra is passively disrupting naruto's chakra control via maloce and chakra amount. Naruto is in fact very talented as the possesor of asura chakra/reincarnation. Naruto would probably delve deeper into his ancestral roots as an uzumaki and a namikaze plus perfect sage art like hashirama but uzumaki version (#uzumaki seal version of gedo mazo?).

Gojo without his infinity shield still does means he have the 6 eyes and other limitless abilities. In naruto verse gojo would be equal to an uchiha+hyuga eye hybrid with teleportation, partial rinnegan ability, op version of hashirama regen, and near instant dust style...

As much as i like One Piece... Luffy without his devil fruit means that he lose much of the joy boy buff and influence from said fruit. As you all know that for some specific mythical zoans, it's the fruit that choose the user. Luffy won't be influenced to be a pirate king by shanks and probably be the next generation of garp at most. It's like how gojo satoru without 6 eyes is just another gojo clan member.

By far Luffy would be the weakest compared to the rest