Gen 2: Proper interaction of critical hits and burn

Normal damage is calculated with boosts, screens, and burn.
If a critical hit happens, then:
Stat level modifications are ignored if they are neutral to or favour the defender.
Reflect and Light Screen defensive boosts are only ignored if stat level modifications were also ignored as a result thereof.
If the attacker is burned, stat level modifications are always ignored.
The attack drop from the burn is only applied when attacker's attack level is higher than defender's defense level (boost).

Therefor:
A critical hit will ignore defensive and offensive buffs/debuffs if the attacker and the defender have the same boost level or the defender has higher boost.
The boosts will be ignored if the attacker is burned, but if the attacker has more boost than the defender, burn reduction still applies.
Burn reduction won't apply on the first case, buffs being the same or defender having more.