you cant catch "strong looking" pokemon yet, if you defeat more gym's, that should help.
the catching charm, head to Circhester, pop into the left hotel. inside the elevator (theres only 1 option) head left last door talk to the doctor and BOOM, you have the catching charm, it enhance's all your cricticall catches, makeing catching pokemon easer P.S. talk to the guy after compleating the 'dex and you get a shiny chary.
the pokedoll, lets you run away from any wild pokemon battle, not trainer/raid though.