Skye effectively counters Kinessa, as first, Kinessa doesn't have any reliable movement strategy, and she cannot self heal. Additionally, Skye can evade Kinessa's shots, unless by some bad luck, gets hit by Kinessa, which means Skye can get close.
Maeve struggles against groups of enemies, so stick close to your team, especially if you are a support, because you can pressure her either fight, where she will most likely lose, or to flee.
As Maeve, try jumping on top of your enemy to confuse them. Players do not tend to aim directly up, so the moment of delay is enough to land a few shots on them.
Never get close to Ruckus. 1. Your damage will be to pitiful to seriously hurt him, and 2. Ruckus's damage will completely shred through Grover like paper, and Blossom will not be effective whatsoever. Moral: stay far from Ruckus.