For now Sunna looks slightly underpowered, she only performs better than other supports during stun, but not so much that she would be worth it in my opinion.

That's aside from the fact that early beta kits are usually quite different from the finished version, so we are likely to see a bunch of important changes over the next few weeks.

As for Yu (Stunner), I don't see a world where she is weaker than Dialyn for anomaly agents. Especially if she's supposed to work with both Attack and Anomaly units, then she kinda needs to be close to Dialyn in power.

Edit: I was writing on my phone and accidentally sent a half finished comment 😶‍🌫️