In Candy Crush Saga level 505 you need to clear the jelly and score 100,000 points.
There are two cake bombs on this level surrounded by double-layered meringue. The bottom row has licorice swirls on it and all of these squares have the double layered jelly underneath. There are just 50 moves to complete the level. Bombs with 12 moves will also fall from the top of the board regularly.
The key to level 505 is to concentrate on unblocking the cake bombs. Ignore the bombs falling down if you can, because once a cake bomb explodes, they will be removed from the board. Try not to complete both cake bombs together as you will not get the advantage of a layer of jelly disappearing each time you complete one. Once the cake bombs have gone there will be some jelly left which you should be able to remove if you have enough moves left. Special candies will always be useful. Stripes can remove multiple slices of cake or multiple squares of jelly as can wrapped candies. A combination of both can be useful as well. Color bombs can be great because you can remove annoying bombs if necessary or get rid of multiple jellies if lots of candies on them are the same color.
This means that color bomb and wrapped and striped candy boosters could be seen as useful on level 505. However, they will get destroyed when you explode the first cake bomb and so they could potentially be wasted and so may not be worth it. A bomb cooler could be better if needed.