[karaterobot]

In my view the question asker can help themselves by asking better questions, if they aren't already. Sometimes people ask vague questions, and it's hard to respond to them, even if you want to. This is something we're working on in my team: ask specifically for what you want, tell the other person that it's important, and also, crucially, tell them when you need the response by.

But, assuming they are already asking good questions and just not getting good responses, they should instead be asking for a synchronous meeting with the other developer. They should be pairing, or screen sharing, or at the very least looking at each other when they talk. An ad hoc 15-minute meeting is a slight pain in the ass, but better than a Slack conversation spanning 2 days, followed by a 25 minute retrospective discussion on what went wrong.

Try to make it part of your team culture that, when somebody is blocked, anybody who can help them needs to put down what they're doing and unblock them as fast as possible. This was a firm rule on the most successful team I ever worked on, and I have carried it forward ever since then. It's better for everybody if they can expect to get help and are expected to give it.