there anything that can only be dropped from hell baal and no other boss / minion in the game?

Well not "no other boss" per se, but an example would be 45 life skillers - even the grand charms being ilvl 99 dropped from him have the casino jackpot chance to be rerolled into a 45 life Skiller

who else can drop 99 ilvl gcs?

Not ilvl99 but high enough to be rerolled for life skillers are Hell Diablo and Nihlathak (can't remember exact ilvls off the top, 94? Someone will come along and correct this)

Edit: I wouldn't put a ton of focus on just these, just for the reason of life Skiller gcs.. I mean, yes, it can happen just like rerolling Baal gcs can happen.. farming lvl 85 areas fast/efficiently/without dying will yield better results in comparison to farming these bosses (that bots farm all day, everyday and 45l skillers don't drop all the time..) for the sole purpose of finding these.. if that makes sense?

This post was edited by Viesh7 on Mar 18 2021 06:54pm

ilvl 91 is required for 41+ life (nila (95), dia (94) and baal (99) can drop em)
there are 3 more of those level 90+ affixes for small charms, not sure if there are any for other items though

ya i was just wondering if baal is the only one that can drop GCs that can only be rolled into 45 life skillers, or tals armor or anything else. like is there a certain item that only hell baal drops that no one else does