Get ready for Zamazenta, Hero dog! As far as fighters go, it’s not there for PvP, or PvE. Maybe someday it will get some move that changes that? But for now it seems more a dex entry and XL farm for later, but everyone loves what they love!
Mewtwo really takes the cake here, with your shadow birds that do better when not purified. Maybe that Metagross that you evolved before it got Meteor Mash might see some non legacy move action!
Go to the official counters page for a complete list including Shadows and Megas to see how your Pokemon perform.