General

Wow, you made an impressive description of the CRA bosses. When they die, do they always drop an equip you can use ?
An attack range of 10-15 mil is abdurd high though, my reboot Ark is like 500m at 199......

It depends on a few things, like what class you are, how much boss and pdr you have, how good your control is and which boss. But either way, fight them. You wouldn't know how far you are from soloing or learn their mechanics it if you never attempted it in the first place.

And you never know, you could always surprise yourself with how far you get. If you're a nightlord hitting 10M-15M lines, you should have enough damage to kill at least Pierre, Queen and Von Bon. If you do more than 15M, you could probably kill vellum too if you have good mechanics.

--- Breakdown of the individual bosses below:

Von Bon is probably the most straight forward boss with 100b, and you could elongate the fight to being up to 16 minutes. But since the last 1/4 of his HP, he's mostly disappearing and re-appearing. I'd say you should be able to average out about 8b every minute to him to to give you enough wiggle room for the meteor phase. But (damage-wise) the hard part about him is when he transfers you to an alternate dimension, and you have to kill his disembodied half with 800M HP within the time (I think it's 15 seconds). Some tips, you can duck to avoid his lazer. Once he starts stomping, there is a long cooldown between stomps, I follow a rule after two lazers, he will stomp again (he didn't disappear randomly for 30s), and every time you return from the other dimension, he will probably stomp.

I find Pierre to be the easiest of the bosses, but he can be very frustrating. He has the lowest of the HPs among the bosses, but about 1/3 of the time is just downtime waiting for the right hats. So you should be averaging around 6b damage to him every minute. Then once both pierres are low, it's making sure you have enough AoE to suicide burst them.

Vellum (mechanically) is probably the most predictable, but you need to learn how to aggro his tails. He also has the most HP, at 200b, is underground most of the fight, and only comes up when he's going to attack you, so he requires the most amount of funding. I'd probably have to say on a dojo dummy, you should be doing around 16b every minute to solo it (this is after factoring in he's physically resistant and has a huge PDR barrier of 300% to over come).

Queen, imo, is the most annoying. She has 140b HP, but she's a punching bag, and (aside from damage reflect), you can keep attacking her non-stop. The hardest thing (damage-wise) about her is she spawns a mirror with 550M hp that after 5 seconds, seduces someone, and kills them, and if they die it heals her. If you lack the dps to burst that mirror down before it kills you, you will fail the solo.