Ruling Serperior's Ability

[imposter_oak]

Okay, so I did a little bit of reading around the forum. Abilities are like powers and bodies. Some are always in play, others are not. Where does Serperior's ability fall here?

The ability reads:

Royal Heal
At any time between turns, heal 10 damage from each of your Pokemon.

"At any time between turns." - Does that mean the damage MUST be healed, or that I may heal it? For instance, if a Zekrom has 6 counters on it and I want to leave them there, do I HAVE to heal him?

Thanks in advance!

 

[DNA]

Serperior's Royal Heal is not an optional Ability. Optional abilities standardly say "you may _______", but since Royal Heal doesn't say 'you may', you must do it every time between turns.