For the first one, yeah poison mystery kinda useless atm with those status (i still use it though sometimes, depend on the situation)

For the other, that would make water main too easy too play, playing according to the enemy, outsmart the enemy with your tactic, pick the best passive, mystery, ninja, etc, all is what you need to play this game. Make water main became that easy is not fair to the other main. Every main got it's own strong side and weakness after all. If you take out the weakness you will make the game too easy to play, and it won't be interesting anymore. Unless if.... Sorry to say this, unless if you didn't smart enough to find the best gameplay. If that's so, better play offline game instead of competitive online game.