These are my current strategies as of 9/1/2020 with my 3:48 video and a mixture of new strategies I have found. You can find my 3:48 video here:

Welcome To Cosmic Smash (Cosmic Bus 707) - As soon as the ball spawns in hit the ball downwards, if done correctly it should bounce between all of the panels in the middle clearing them out. Go to left and trick smash the top, then bottom and repeat on right side. Stay on right side for easy set up of next level.

Koori - Trick smash top panels, then bottom.

DonDon - This one can get a bit tricky...start with a normal hit in the middle, then hit the right panel. Depending on the angle you can try and get the ball to bounce off the wall and hit behind the left panel. If done correctly when the next panel spawns in it will destroy it instantly. Destroy the top right panel, then bottom right panel. Use the same technique as the double left done earlier but instead with a high left hit. Hit the long right panel. Trick smash to teleport the ball in front of you and destroy the last remaining panel.

Fusuma - Edge yourself a little left from center and wait for the moving block to inch out of the way. Regular trick smash as soon as you can.

Kusabi - Trick smash the middle panels, then the right panels.

Saikoro - Smash the middle panel to release all the extra balls, and hit medium to low as most of the time in my experience the extra balls take care of the high ones. It can change so read accordingly to the situation, I'm not sure if there's a pattern to follow or some sort of trick yet, as this one is one of my "leave luck to heaven" stages.

Totsu - Wait for the panels to come to the middle and trick smash downwards.

Nami - This is a really tricky one as the first hit and body positioning matter the most. Stand offset left of the middle and let the ball bounce up to your abdomen/torso area then hit right. Move to direct middle and hit left, making yourself off center to the right. Hit right again, recenter. Hit right again, then off center right and hit left. Move far right where the ball bounces and hit left directly into the last plate. This is probably the only strategy I've been able to pull off semi consistently, there is most likely a faster way.

GuruGuru - This one I don't have a strat yet, but as far as I'm aware just make sure both sides overlap as much as possible to get as many plates destroyed at once.

Shuu Gou - This one is tough too, as I'm not sure what the proper angle/timing is. All I know is that a trick shot will help clear a lot at once.

Haribote - As soon as the ball spawns in hit it left. It will go behind the moving blockade and bounce off of it to destroy the two yellow panels.

Hami Gaki - I do not have a strategy for this one fully formed, all I know what helps is waiting a second then hitting the ball downwards to bounce up and destroy the middle two panels, then hitting it up left to destroy the high left one, bounce off of the blockade and destroy the middle left one. I repeat that high left process with the right side, then get the two low ones. Haven't gotten this one consistently yet.

Sho Dou - Stand direct middle and let the ball reach lower torso/high abdomen, then hit the ball high left. Get whatever panels aren't being destroyed.

As long as you don't finish 8 of the 13 stages with a trick shot (so far I've only done 7) you will not activate the bonus stage and ruin the run.

As of right now with certain strats done my timer is saying the best possible time is 3:09, but this could possibly be shortened if new techniques are found. This guide will be updated once I find more strategies. Hopefully I can do a run with all of them successfully recorded.