State of Galio
He did everything good, he got nerfed. He's now a C list level Support that builds full tanky and banks on his flash taunt/ult cc. You cannot take him into a solo lane period since his wave clear is shit and his sustain/survival is non existent without building all tank items. He's completely dependent on Aftershock as his keystone now with no other effective means of play.
There was a great way to balance Galio, and Riot failed to do so in favor of simply removing him from all lanes and gutting him into a cc bot support.
My solutions in depth - Galio is in a state of flux where his role is poorly defined. Riot should either;
A) Take a hard look at his numbers and adjust him better into the AP Bruiser role by making the base damage on his Q bigger, while gutting the scaling and making it do %hp damage so it doesn't go completely out of control into late game and he can still duel but not totally nuke squishies with it. Also reduce the range of his ult so he has to rely on teleport and walking to set up roaming from top/mid better and provide counter play/warning for his enemies. Increase his base HP, Armor, and Magic Resist a tiny bit. Boom. Balanced AP Bruiser that doesn't ridiculously wave clear or nuke people with a couple items while being unkillable.
B) Go FULL Tank Support Galio. Nerf his AP scaling a small amount across the board but compensate by doubling down on his defenses and cc. Have his Q provide a speed boost for allies that walk through it or a tiny slow to enemies that remain in the gale for too long. Buff the taunt to be either slightly bigger, the max duration at all charges, or buff the tank stats it gives so he can do his job more consistently with his now lack luster damage. Put the shield back on his ult, improve the knock up, gimp the damage.
Either is a clearly defined direction for the champ, makes him more valuable than he is now, and each is much easier to balance in the long term because you're not having to account for multiple lane/roles. MGGA! 
[galio-happy]
