"Power" isn't a real thing. It's a number that is used in game. It's calculated using some formula and all it really does is give you sort of a summarized view of the teams overall stats all reduced down to a single number.
If they changed how that number is calculated, then the summary will change. But the stats for each individual character are unchanged, and those numbers are what really matter in a battle. That's what your attacks, defense, etc. are all based on - and they aren't changed.
So a change to the power number should NOT have any effect on your teams performance in a battle.
