Ugh, the last autoscroll level (minus the Kamek autoscroll in 6-8). Luckily, the second half of the autoscroller can be skipped by using a perfect jump. A first-frame jump after landing on the ledge above the pink block will keep the camera scrolled down. This is useful because when landing normally the camera would scroll up and moving to the right load in the trigger for the autoscroller to start. But instead Yoshi can then just flutter past the flower and land on the downwards slope, avoiding the trigger that starts the autoscroller entirely. If you hold right the whole time you only have to flutter twice (make sure you're holding B as you fall to the ground) but if you hesitate at all you will need to flutter a third time. This skip saves ~25 seconds. Just watch the video if you have trouble understanding this explanation - it will be very obvious.
The chomp rocks in the last room can be unpredictable since they spawn at different times depending on how high the camera is scrolled. It's possible to make it through without slowing down at all but you may want to take it safe as it's very easy to die here.
The top video jumps over the final red coin which saves time on the score screen if you avoid all the red coins in room 1. You shouldn't get a bonus from collecting the flower unless you grabbed a flower in room 1.
SUPER COOL ROCK BOOST
This saves about 1.5 seconds. You can also bring a shyguy to bounce on to get up rather than perfect fluttering. Hold right and then let go after you hear the rock roll 3 times. Start holding right again when the wall to the left goes completely off screen. Once the rock falls down jump to the right to get down.
You can do the following to swag up your 6-5 for infinite swag points... and it's actually really easy to do as well!
TRUST THE SETUP!!!
1) You stand to the right side of the flame
2) You wait and jump at the right moment (Keep holding jump until your flutter is over) - DO NOT MOVE YET! (Do not touch your Dpad at all)
3) You wait until the pipe appears - That's the moment where you want to press JUMP and then LEFT and you keep holding both. You will do a flutter because of it, then headbonk, and do an automatic second flutter because of it (You want this to happen). You can just keep holding left until you are 100% sure to be safe.