Thank you.
So, there, she's only throwing the syringes from a few meters away at best. And she's only throwing them one at a time.
Honestly, Kongou seems the more likely to win here. She can just set down a few ejection points (which don't seem to have any kind of visible mark) and then run away, forcing Bubble to chase her where she can activate her ejection point. Also, since Bubble has to manually carry all of his syringes, she can just fire a tree, bench, or anything that's around at him to make him drop his syringes. She can also make ejection points right in front of her to blow away any attacks from the front. The syringes aren't getting through that without being pushed upwards and harmlessly away from her.
Kongou is much more intelligent than Bubble. Not that Bubble is foolish, but average intelligence compared to above average intelligence that has more fighting experience gives Kongou a necessary edge in strategy and fighting capability. I can see her winning more often than not.
Plus, Bubble can run out of/have his syringes broken. Kongou has no such problem. Since they're starting a good distance away, then there's going to be no point black syringe throwing shenanigans that she cannot avoid. She'll likely keep her distance since that's what her ability requires of her.
Please toss in a vote for Kongou.