Spoilers for B2 in in ascending spoilerishness:
- The big black gap is 5 units wide, big slime is 3 units, small slime is 1 unit.
- Small slime needs to "bridge the gap" somehow.
- Small slime needs to be in the middle of the black gap.
- Small slime needs to be on top of big slime first.
- Then push big slime with small slime on top to the edge and push small lime down to the ground.
- Finally, get into big slime, wobble over the small-slime-bridge and finish.