[RBG*]

How to get castle Points: (taken from the Nintendo Guidebook)

Feat:

# of Pokemon that have not fainted = x3 CP (i.e. if 2 pokemon of yours are alive, you get 6 points)
# of Pokemon with no Status Ailments = x1 CP
# of foe's Pokemon that you give +5 Levels = x7 CP

Only get one of the following for each pokemon:
# of Pokemon with full HP= x3 CP
# of Pokemon with >50% = x2 CP
# of Pokemon with <50% = x1 CP

You only get one of these per battle:
If <5 PP used in battle = 8 CP
If <10 PP used in battle = 6 CP
if < 15 PP used in battle = 4 CP

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What you should do Battles 1-20:

Raise each of the opponents levels by 5 (costs 1 CP to do for each pokemon) and lead with a fast strong sweeper. If you do a 3-0 Sweep you will have achieved a net gain of 47 CP (50 total CP minus the 3 you spent to up levels)

So far, after battle 28, I have 778 Castle Points, only healing my pokes a few times and buying the max Items Upgrade. You shouldn't need to restore PP assuming you have used PP ups and are sweeping fast, and viewing your opponents pokemon's moves seems unnecessary, so don't spend money on those Level Ups.