Genestealer Brood

Tyranids with rending claws inflict a wound automatically and ignore armour saves on to-hit rolls of 6. Other successful hits must roll ot wound as normal. If the creature rolls a 6 for Armour Penetration they then can roll an additional dice to determine the total Armour Penetration value.

Squad may deploy using Infiltrators special rule

Genestealers outside the range of Synapse creatures do not use the instinctive behavior rules, but instead must take Morale and Pinning tests like ordinary troops.

If the Tyranid player gets to choose the scenario then the Tyranids will automatically be the attackers and must choose a scenario from the category of Battle.
All three missions under Battle use the Deep Strike rule, and all models in the Tyranid Seeding Swarm must arrive on the table by this method. The exception are Tyranid broods with the infiltrate rule and Lictors.
For all other scenarios, if the Deep Strike option exists it can only be used by Tyranid units with the Deep Strike rule.