Is Hanzo’s Ultimate Global

Mercy charges her ultimate in the following way:

• Passively charges 1% per 2 seconds
• 1% per 10 damage done with pistol or melee
• 1% per 12.5 damage healed (self-inflicted damage such as S:76's or Pharah's rockets do not charge your ult)
• 1% per 15 damage done by amped ally (Mercy's damage-boosting blue beam)

The fastest way to charge your ult, therefore, is to avoid sticking to one ally unless they're dealing consistent damage. As soon as someone is topped off, either find another ally or begin damage-boosting.

Other than breaking line of sight, there is no general way of "dodging" it. There are character specific skills you can use to avoid it.

• Reaper - Wraith Form
• Mei - Ice Block
• Genji Deflect(will generally one shot the mcree or anyone else you're targeting while deflecting btw, damage is based on the time the mcree channels before firing.)
• Reinhardt/Winston/Zarya shields seem to work as well, though I've never done this myself.

Basically anything that can make you immune to projectile damage should work, if timed properly. Otherwise, your only option is to kill him first or break line of sight.