Accepted Answer

  1. You can achieve these milestones either solo or with the help of a friend in Co-op (or from the help of yourself if you have good dexterity and can use two controllers at once....). My current Solo high score is with Ness at 526.747 km. This is the attack pattern I used:

    Stage 1
    Forward Smash → PK Fire (Side Special) → Forward Smash → PK Fire (Side Special) → Forward Smash

    Don't wait for the PK Fire to end before using the Forward Smash. There is no time to waste! Also it's the PK Fire preventing Sandbag from launching and breaking the barrier when you use the forward smash. Note that each PK Fire will cause you to move slightly backwards away from Sandbag. This will result in the forward smashes missing. Try and move a tiny bit forward before each smash attack to counter this.

    At this point the 5 second warning should appear. Now do:

    Stage 2
    PK Fire (Side Special) x 4

    There will now be about 1 second left. Run Over, pick up the Home-Run Bat and launch Sandbag with it! The timings are really tight but it is doable once you practice it. Keep in mind that the Sandbag can't be on fire by the time the bat hits it as that will prevent it from launching. Also if you get the dramatic effect when you land a forward smash you likely won't have enough time to do the above pattern and will have to try again.

    Source: Robeson's Super Smash Bros. Ultimate Guide