[2020] Anyone have any advice for the current global event?

Usually there's a tips and tricks post, but I haven't been able to find it so far. Specifically, I'm looking for help with a) weak point kills and b) kill a guardian with another guardian's explosion. How can I do these without spending a ton of time? I tried Fed. Bunker for weak points, but only one of the bombers was a guardian, so it seemed like it would take forever. I've done all the day one challenges and the obvious ones (melee, pictures, etc.) Also, the skill kill veteran guardians challenge.