hype and master gee always have the same stats no matter how many players fight them, its always set to 4 player, i cant help you much with axton or krieg as ive never really used either one, ive also never had vermi grace my presence, tried a lot to no avail, however, with hype, the key is to deal enough damage to the 4 loaders that he spawns to transfer his shield, you need to do it quickly so that you have a decent amount of time to deal damage to hype himself, eventually, if you havent dealt enough damage to hype, the bots will get the shields back and you have to remove them once again to deal damage
edit… as far as using zero goes against hype, there are a ton of videos out there showing how bore is used to kill hype, with Sal, my preference for raid bosses actually runs towards the pimp/nukem build

The other raids (as far as I know) are scaled to around 32 in Normal mode. In UVHM, they’re all scaled to your level. I’ve only done the other raids once in Normal, so I can’t really say much about it, but IIRC they were quite easy in Normal compared to TVHM.