Zam's frailty isn't necessarily detrimental to its use of Magic Guard - it means it gets a free LO and 4 subs guaranteed if it can get a free switch. Being able to come in on Burn/Poison is also very useful, as last gen a sub+3 atks set would often run out of health before being able to break anything significantly. The added usefulness of Psychic attacks in this meta also gives him some usage potential, which is nice.