Shadow Ball or Punishment on Lugia?

Question

It has calm mind, so if I spam that then punishment will get more powerful. Or should I stick with shadowball since Calm mind boosts sp. Atk? Which is most reliable?

Answer 1

Punishment is not dependent of your stat changes. It is dependent of your opponent's stat changes. So go with shadow ball because punishment will not get boosted at all from calm mind and shadow ball will.
Source: http://bulbapedia.bulbagarden.net/wiki/Punishment

Answer 2

Punishment does more damage if your opponent raises its stats, not you. So go with Shadow Ball. But I wouldn't do either, personally. This set is great:

Staller/annoyer Lugia @ Leftovers
252 / SDef / 252 HP
Recover
Substitute
Roar
Thunder Wave

Answer 3

Well, I don't really like CM lugia. It's really supposed to be a wall. But in this case it would have to be Shadow ball. The reason being is that punishment increases in power the more boosts your opponent has not you. So you'll be getting no boost from it. Shadow balll also just is baws in general :D

But seriously use a walling set.

Lugia @ Leftovers
Trait: Multiscale
EVs: 252 Def / 252 SDef / 4 HP
Serious Nature
- Toxic
- Substitute
- Whirlwind
- Roost

This capitalizes on Lugias epic 106 / 130 / 154 defenses. It can take virtually any attack at full health. it then can set up any sub and blow the opponent away with whirlwind or toxic them for greater damage.

Hope I helped.