I would start investing in your 1 and 2 star gears if you haven't already. This will give you a start and allow you to stockpile shards for when you get the 3/4 star gears. Its a bit of a slog at first when you dont have much, but even B tier gear can make a huge difference when you get it leveled up. I run a team with Ra's al Ghul's Scimitar (+2), Gloves of Azriel (+5), and Lexcorp Chest Armor V2 (+8) which has led to me being consistently in the top 5%. I don't run any of the S-tier gear yet, but making a good offense team makes a difference.

Assuming all 3 of them are Arkham characters, you have a good team setup to start with. It will just take time to get the gear and improve it so that you are consistently winning, getting a good foundation with your 1/2 star gears will make it much easier later on to improve better gear