Over Each new season brings new characters with varying degrees of power but the most recent line-up is definitely the strongest iteration of the group.
While some characters are clearly more essential than others, all of them have a part to play and are vital to making the group of misfit superheroes traveling through time feel like an actual team.
Ava
Ava Sharpe is co-captain of the Waverider and girlfriend of Sara Lance, the ship's other co-captain. Despite being a clone from the future, Ava doesn't seem to have any futuristic powers or abilities that give her an advantage.
However, she is an extremely skilled fighter and seems to be on the same level as characters like Sara who was trained for years by the League of Assasins.
Rory
Unlike most of the Flash's villains, Mick Rory aka Heatwave isn't a metahuman and instead relies on his heat gun as his primary weapon, which was originally created by Cisco Ramon.
The only ability he might still possess is an extended lifespan that he received from the time masters during the time he served them as Chronos.
Sara Lance
Sara Lance aka the White Canary is the Captain of the Waverider, taking over for Rip after he left the ship. While Sara Lance doesn't usually possess superhuman abilities, she has demonstrated an ability to use them such as when she wielded the death totem or when she survived an attack by the Atropos and gained prophetic sight which allowed her to see the future temporarily.
Although she does get the occasional power boost, she mostly relies on her skills as a leader and her training as a former member of the League of Assasins.
Nate
Nate Heywood is a former history professor and the grandson of Commander Steel, a former member of the Justice Society of America. When Ray injected Nate with the enhancement serum he modified that was created by Eobard Thawne, Nate gained the ability to turn his skin into a form of an alloy, making him pretty much invulnerable.
The transformation grants him superhuman strength which has allowed him to pull off some amazing feats like stopping a train and acting as a superconductor for the Waverider.
Atom
Using his skills as a scientist and an engineer, Dr. Ray Palmer was able to create an exo-suit that allows him to alter his size naming it the ATOM suit. Not only can he shrink himself and other objects, but his suit also has the ability to grow to enormous heights.
The suit can also fly and shoot energy blasts but even without it, his genius-level intellect made him one of the most valuable of the team before he eventually left the ship.
Zari
Both Zaris and Behrad get their powers from their connection to the Air Totem which had been in their family for decades. The air totem is one of the 6 totems of Zambesi and allows them to harness and control air using things like wind blasts and shields.
It is also where the original version of Zari resides since it serves as a connection for the holder to previous bearers of the totem. Behrad is the more skilled of the two since he's been using the totem for longer but his sister seems to be just as proficient as he is in wielding it.
Nora
Nora Darhk is the daughter of Damien Darhk and like her father, she was a powerful sorcerer who was skilled in the dark arts. In season 4, she received a power boost when she became a Fairy Godmother due to her getting the magical wand of the former Godmother, Tabitha.
The wand provided her a wide range of different powers that allowed her to make any wish come true with the only limitation of her power being that it had to be a wish requested by whomever she's serving at the moment which was usually a child.
Astra
Despite initially being an antagonist, Astra Logue became a member near the end of the season and will continue to be on the team going into season 6. Since she spends a large part of her life in Hell she was able to learn a lot and although she isn't as powerful as John, she is still a capable of Dark magic.
The best demonstrations of her abilities were when she used her powers to resurrect the various encores to use against the Legends. Her mystical knowledge is vast, even if she doesn't use her powers that much in practice.
Constantine
As the team's main magic-, John Constantine is one of the strongest . John became a master of the mystic and dark arts after being introduced to them by a nun named Anne.
After extensive studying and practice, he became proficient in a number of spells that give him a variety of powers like the ability to use telekinesis, travel between realms and dimensions, and even the ability to conjure or banish souls. His abilities and knowledge have been extremely useful in helping the team getting out of situations that science and time travel couldn't solve.
Charlie
Charlie is a shapeshifter that was later revealed to be the goddess, Clotho, one of the three fates and one of the guardians of the Loom of Fate. As a spinner of the loom, Clotho's job was to spin the life threads which resulted in the birth of new lives and destinies.
As a god, she has a wide range of abilities including immortality, multiversal travel, and the ability to kill others with her true form, which makes her the strongest member of the team. The only Legend that was able to do any sort of damage to her was Constantine with him taking away her ability to shapeshift for a short period after their first encounter.