Hail to the new fighting king?
If Power-Up Punch, a 3 bar charged move, boosts attack 100% of the time like it does in the main series, do you think that Lucario will become the new defacto fighting type PVP king?
....if so, I'd better hurry up and hatch some 7k eggs!
Answers
It looks like the chance might be 100% - in the game master for the move it says "buff atk ratio 1", which seems like a 100% chance. I'm guessing it's only one stage,or a 25% buff (all the other's have been two stages, or 50%), and it's only for attack, not both defense and attack like the other buffed moves have been. Given that the move itself is not very good, I wouldn't be shocked if it's a guarantee.
Well, better safe than sorry, I guess, since this game is basically a constant patience test in which we have to wait before making decisions as long as there's a believable chance that what we want will become better later but in a way that's not retroactive
We still need some luck to get good IV Pokemon from raid/community day, which is a good enough reason to not do anything until you have more than one option