real quick, if you wanted to use more that 1 costume for the “Lemons” (or Asteroids, if your doing what i am), then i have some useful inserts.
1. go to the “Lemon” (or asteroid) sprite. Then, make a variable named “cost-set”. then, in the costume block in your Lemon Spawning custom block definition (i named it “spwn-enmy”)
add a “pick random” operator in the “Switch costume to:” block. After that, make as many costumes as you want, and go back to that “pick random” operator, and put the number of lemon (or Asteroid!!!) costumes are there (Exclude the “BIG” sprite). After that, add a “Set cost-set to:” block, and add the “costume number” operator in “Looks”. It should look something like this:

define spwn-enmy
switch costume to [BIG]
go to x: (0) y: (0)
set [dir] to (pick random (-180) to (180))
point in direction (dir)
move (-350) steps
switch costume to (pick random (1) to (4))
set [speed] to [1]
create clone of [myself]
set [cost-set] to (costume #)

Then, go to the “when i start as a clone” script, and add a “switch costume to” block to the end of the script inside of the forever loop. Add a “cost-set” variable reporter, and test it.

Hello! It's great that you want to help out other Scratchers. However, I think we have enough guides in the forums at the moment. Please feel free to welcome new Scratchers on the group welcoming topic or on individual topics created by New Scratchers.

Other places that can always use more helpful Scratchers like you, are the "Help With Scripts“ and ”Questions About Scratch" areas - please use them as designed, by responding to topics created by folks with problems to solve

Finally, a really good place for Scratch guides is the Scratch Wiki - check it out and see if it's something you might like to work on. They have a number of guides - and great organization.