I'm pretty sure Vishnu's existence in high level Challenges denies Gabriel's existence. Talking about the enemy recovering HP pretty much triggers ccool.
This is true. It's less about the recovering HP and more about the resist, but yeah. I mean, I can accept that recovering is his gimmick, but the fact that he's green is what makes him virtually impossible. If he wasn't I could beat him fairly easily.
I going to blindly assume that Gabriel isn't the best water team there is out there. Does Vishnu counter a good majority of water teams or just Gabriel and a couple others?
No, Gabriel is not the best blue team. Not even close I'm sure. There are certainly better blue teams that can beat Vishnu, but they tend to be kind of whale-y in my experience. Meanwhile, Gabriel is becoming less strict to build since Reine is no longer really necessary, Snow White is easy to get, and the proliferation of rows means the Sun Quan slot is now a flex slot that could be a few different things.
Since Friday; it really is pretty awesome. Even better if you've got an Ares, Artemis, or I&I to skill up (I remember CRAB used to be Hermes at one point but I guess it isn't now?)
I don't have any of those actually, but incidentally I've been playing Groove Coaster a lot lately. It, uh... Isn't like the collab at all. :V
CCool is mostly a stall-team player, which would be completely fine if stall wasn't effectively a playstyle that only gets the middle finger in this game. Pretty much every dungeon is designed to require insane amounts of burst and yet also be a pain in the ass to burst down. If that wasn't the case I'm fairly sure CCool wouldn't even use Beyzul on his team - just as much as I wouldn't absolutely need Wangren on my eventual Red Stall team.
CCool also hates green enemies with a passion for rather obvious reasons, and Vishnu is the ultimate fuck you to just about everyone ever, blue and red teams especially (but mostly blue). I'm pretty sure CCool once spent around 100 turns trying to deal with Vishnu before finally going down because let's face it, Enemy!Vishnu is a dick.
Oh, it was well over 100 turns. And as far as Vishnu being a fuck you to everyone ever goes, again he would not be a problem at all for Gabriel if he wasn't green. Gabriel would barely be threatened by him if he wasn't green. He would take a lot of actives to beat so he might be a serious problem if the next floor requires a quick response, but he doesn't even theoretically require a leader swap. I have to assume this means similar bulky teams with similar burst potential don't really care about him that much. He's definitely a fuck you to spike teams, but tank teams packing a decent delay and decent damage handle him extremely well despite his regeneration. At least I assume they do, on paper they do, but I can't confirm because I've NEVER FUCKING BEATEN HIM.
Also, let's not forget Awoken Meimei's complacency in all of this. I couldn't even bring Beyzul into that dungeon where I fought him for over a hundred turns because I HAD to bring NepDra to deal with Meimei. And again, if she wasn't green I could just burst her. Although I acknowledge that she does resist multiple colors so she's troublesome for more than just blue, but she resists blue the most. And stacking two massively, ridiculously bulky green enemies in the same dungeon is bullshit. At least skill inheritance theoretically takes care of her, it totally doesn't for Vishnu since I can't inherit fucking puppets.
Edit:
Cmon ! That was just a small vent ! Yea, i get it ! Water get resisted by all Wood Atts. ! But other people here run RBG Teams too, even i am making and running a Skuld Team and building a Wood Row Team, i know, you have bad memories of being att. countered alot of times and on very important stuff, but others have too, and they aren't complaining about me complaining that i had a hard time with a enemy that kept trolling me and made me waste 35 turns just on dealing damage for it to be healed.
td;dr: You have bad memories, i understand, but at least let me just vent a bit, at least you have your husbando, i have neither Waifuterasu or Daughtermiel, sorry if i made you mad, please understand. (I can't make proper tl;drs.) 
What I'll say to that is, if you NEED built-in double damage to beat Doomsday then you've probably got other problems. Fair enough if that's just not bringing weak leads into the dungeon to get pal points, but relying on having type advantage isn't really that productive. Being resisted is one thing, but just not being super effective is another.
And I didn't decide Gabriel was husbando before I pulled him, I pulled him and then he became husbando. I recall that I was actually fishing for I&I that day and I was a little disappointed to have him at first. I've said this before and I'll say it again if I have to, don't get too attached to cards you don't own. I did that with Andromeda, I still don't have Andromeda, and it was basically just a huge waste of time and resources. Figure out which things you do own are good, then get attached to them.
Edit edit: Oh yeah, and as far as most people not harping on your every time you bring this up goes, I'll say two things: One, most people just run white or black and don't have this problem. That is because they are superior colors that get free handicaps for some reason. Two, I'm just busting your balls to some degree. Don't take it TOO personally.
I do actually mean everything I'm saying here, but it is in part for humor.
