This would be a lot clearer if the feats were listed in the OP.
Minecraft has 2 main 8-B feats rn, to my knowledge. Charged Creeper explosions and Wither Spawn Explosions. There's also Creeper explosions and the old Ender Dragon ramming calc which are both High 8-C. I'll go over each calc in turn, with arguments for and against.
Charged Creeper Explosions (21.33 tons): There are two metrics that can be used to determine whether mobs should scale to this - Minecraft 'lore' and physical feats, and game damage scaling (less reliable).
For the former, Charged Creeper explosions are unable to destroy Netherite blocks, under any circumstance. However, the Ender Dragon is capable of destroying these blocks (multiple at once, in fact), as is the Wither Boss with its ramming attack and blue skulls. Some would argue that as the Ender Dragon can't destroy Obsidian or Crying Obsidian, that it is game mechanics for it to destroy blocks of similar strength. I disagree. For the former, the Ender Dragon is unable to destroy blocks present in the End mainland, including Iron Bars (but it can destroy Iron Blocks), End Stone (but it can destroy End Stone Bricks), etc. Also, there's evidence that Obby, Crying Obby and Respawn Anchors are more dense than Netherite - none of these blocks can be pushed by a piston. Finally, the Wither can destroy Obby anyways, so yeah.
For the latter, both the Wither and Ender Dragon can comfortably survive multiple charged Creeper explosions. Charged Creepers deal 85 damage according to the wiki at their max explosion power. This is reduced further when considering that the Ender Dragon takes around 1/4 of damage not dealt to its head, and that it is physically impossible for a Charged Creeper to deal the theoretical max damage. Seriously, I've tested similar stuff, the Creepers dont deal max damage even at point-blank range. For them to do max damage they'd have to be inside of the mob when exploding, which is, well, wrong. Which is one problem with using mc wiki values for scaling. But yeah, both the Wither + EDragon can take multiple booms and comparable mobs can harm them.
tl;dr 1: No matter which metric you use, boss mobs should scale to Charged Creepers.
Wither Boss Explosions (38.5 tons): I mean, this obviously scales to the Wither in some capacity. The Dragon and Wither can survive multiple of these in theory, and the Wither performs this feat like 3 times in Bedrock Edition afaik. I'd say this is the upper limit of what the EDragon and Wither can do in terms of feats - they are above Charged Creeper explosions and below Wither explosions.
Ender Dragon Ramming (like 4.5 tons or something): I don't really care either way, the calc is based somewhat on assumptions about how many blocks the Ender Dragon can destroy at once, but it is a feat. The blocks are destroyed through physical force, no entities interact the same way with the EDragon proving that it's not some weird passive EE or BFR armour or something, the fact that it was originally intended to just be a workaround for weird collisions is irrelevant as Minecraft has been through countless updates since then, including direct revamps to the EDragon fight itself.
Mobs scaling to Bosses: Nah. This relied heavily on game mechanics, but in terms of feats it would be ridiculous to scale mobs to boss tiers when most of them get fodderized by High 8-C Creeper explosions. There's also an argument that it's stated Endermen are a threat to late-game Players in the Mobestiary, but I honestly don't see that interpretation. If you read both the EDragon and Endermen pages it implies moreso that the Endermen are only a threat during the EDragon boss fight due to their large numbers (which is true in-game, I mean you would have needed to kill around a dozen Endermen to get to the End anyway). And Endermen are decently above other fodder too.
Proposed Scaling: Creepers, Charged Creepers and Wither's birth attack should scale to their own feats, obviously. The Wither and Ender Dragon's regular attacks should scale above the Charged Creeper's feat but below the Wither Explosion (21.33 < them < 38.5). Iron Golems can fight a Wither to about half health, so they backscale, and Ravagers are comparable to Iron Golems so they scale too. Some strong mobs, like Piglin Brutes, Elder Guardians and Shulkers (durability-wise) scale to Creepers/High 8-C (3.53 tons). Not keen on Elder Guardians scaling to bosses just because it has a boss bar in one version, or Endermen and Hoglins scaling to Creepers as they barely survive the explosions. The Ghast has an 8-C feat (0.31 tons) that it can scale to (AP only), mobs that don't scale to the Ghast would instead upscale from the Silverfish (> 0.016 tons).
tl;dr 2: Scaling goes 38.5 tons < Wither + EDragon < Iron Golem <= 21.33 tons, strong mobs = Creepers = 3.53 tons, other mobs either scale to 0.31 tons or are >= 0.016 tons.
This is probably going to be the most motivated I am to speak on this topic for like the fourth time, so I hope that covers everything.
