The problem with Kiawe is that your turn ends without being able to attack. If you get KO'd by your opponent in the next turn - and there are going to be plenty of decks out there in August that will hit for a lot of damage really early in the game - you basically just blew your game.
Look at it this way: If you Kiawe on a Pokemon and you're going up against Gardy GX, Gardy will do AT LEAST 180 to you on the next turn. I'm not saying there's not a place in the meta for Kiawe - it's one of my top ten cards in BUS - but I'm not sure that it's meta defining.
Just to come back on this (very late, I know). There is no problem with Kiawe at all. Ending your turn without being able to attack still means your giving up 1 attack for something that you could only normally archieve with 3-4 turns of putting regular energy on Pokemon. You have the choice where to put those 4, if you do this on a pokemon that is going to get KO'd next turn the player can be what I consider to be a bad player. Blowing your own game is also another choice in this matter.
If you start and have Kiawe your opponent cannot Gardy GX and will run prizes behind. Once it does 180 damage there is nothing that actually stopes the engine with Volcanion EX from allowing you to 1HKO the Gardy GX back.
It boils down to understanding the deck and Pokemon you work Kiawe with. If you run 1 Kiawe with a couple of Tapu Lele's the whole effect is way to random.
If you increase the factor of it showing up turn 1 and/or 2 your well set up to snowball the whole game. Nice as Gardy GX is this is still a stage 2 which requires drastic set ups and without VS Seeker re-filling that hand isn't half as easy as it is now.