There are scenes of impactful, but fantastical, violence in which mutants and aliens battle each other with a variety of powers.
One battle features stabbings and neck-breaks, but without strong detail.
"Magneto" crushes some villains in a train wagon. You briefly see the aliens being crushed but there's no bloody injury.
There is little actual gore. In one scene one person is impaled in a somewhat bloody manner. But overall, the body-count is through the roof and intentional killings, while real-life understandable, are way beyond comic book.
A character goes on a crazy rampage killing people by touching their heads and disinagrating them.
A character gets stabbed in the back but heals instantly
Quicksilver is seen with a bloody face after Jean grey throws him.
PG-13 violence type: blood and gore.