So this is triple-tap every 2 turns? That's probably balanced against Goldmeadow Harrier because tapping down your team every other turn doesn't keep me alive.

Exactly.

Like the other chargeups, this suffers from the problem that it actually takes three turns to use once. Suggestions for fixing this include

a) Change Chargeup to include "ETBs with a charge counter"
b) Put "ETBs with a charge counter" as a rider on all Chargeup cards.

Actually only takes 2 turns (as it couldn't use the ability the turn it was summoned anyway). Also, if the set has ways to cheat extra charge counters onto permanents (and it would need to have them), this becomes way too powerful. As printed, would need to be uncommon. To stay at common I'd either drop the target creatures to 2 or add to the casting cost.

I'm not convinced it's overpowered, although White does have the ability to add counters. Needs proper testing. Tapping 2 might be fine.

Probably will move this to Uncommon, transferring the ability on (((Cisaean Lionrite))) to this card.

I thought monowhite didn't get bonuses more than +2/+2, to keep it separate from green?