Just tried the instant motivation drop sync attack, with another Instinct player with 2 phones.
It's easier said than done. It needs to be planned properly.
In the end, the Mystic gym ended up with 6 new mons.
The biggest challenges were:
1: Beating Blissey within the time limit on all 3 phones, and within 1 second of each other. Even with Machamps, it's not always easy.
2: Making sure all 3 phones have charge attacks charged up when the defenders all have low enough HP to be KOed by a single charge attack.
Answers
The exploit existing doesn't bother me so much because GRB defense is too strong and it's challenging to pull off with a possibility of disruption by spoiler accounts. In other words it'd be nearly impossible to use it to take over an gym about to host an EX raid because there will be so many accounts attacking and defending at once.
Ultimately gym battling needs a rework and a rebalance, because a meta defined by timing out against Blissey is pretty stupid.
It's definitely quite challenging in practice with 3 accounts given the Blissey time-out problem. You're safer with 4-5 accounts trying to pull this off. A couple of things:
1. Even if the Blissey isn't beaten exactly simultaneously on all three accounts, it still counts as three separate instances of battle that when completed will completely demotivate the Pokemon. So if the timing isn't exact, you will probably still knock it out before the defender has time to respond provided it's within 4-5 seconds or so given server lag. So, as long as you finish the battle on the first account without timing out, even if you can't quite knock it down all at once to pull it off perfectly, you'll probably still succeed in knocking it out before a GRB comes in.
2. Most people only GRB after 2/3 motivation is already gone (i.e. after 2 attacks), so an easier workaround that you can pull off with two accounts is to attack it once, then do the trick with two accounts to take it from 2/3 to 0. I've had people get wise to the trick and berry immediately after one attack, but generally speaking this works rather well and you don't end up timing out on the first account vs. Blissey.
