You're trying to do what I feared you might be trying to do: create a new "thing".
The effects of these Likes aren't important, and can be scripted just fine. That would be the very very easy part.
PBS files aren't things you just write and they'll be compiled just because they're in the PBS folder. Search the scripts for "pokemon.txt", and you'll see it mentioned in the Compiler script section. The scripts know beforehand which PBS files it expects, and there are extensive scripts that deal with them and do the compiling. Any files in the PBS folder that it doesn't expect aren't looked at at all.
The same goes for lines within pokemon.txt. The scripts don't say what to do with a line beginning "Likes=", so it ignores that line. The information in the Likes line is never compiled and saved elsewhere for actual use. You can write whatever nonsense you want in pokemon.txt, but the only lines that are actually looked at are the ones beginning "blah=", where "blah" are the words in the tables in the wiki's
Defining a species page.
You can add some code to make the game recognise a "Likes=" line, and say what to do with the information therein. However, this requires that the information is meaningful (a number or an already-defined "thing"), and that you also know the data structure of a Pokémon species to make sure you save the information correctly and in the right format. You would then need to load the appropriate information later on using this knowledge, and find the appropriate sub-information (i.e. the description based on the ID number), and then display it/use it to determine an effect. That's
at the very least. If you want to define a new "thing" for Likes, that's a whole new and much larger kettle of fish
in itself.
The reason you got something to work when you renamed "likes.txt" to "abilities.txt" is because the game decided that Bananas and Socks were abilities, and you just happened to use the same PBS data structure to "define" them. That's not a sign that you've done anything right, just that you can
edit the list of possible abilities (which frankly, isn't hard).
My point is that there's a lot more involved than you think, and you shouldn't be trying to do anything like this. At all. It's way too easy to mess up, even for me who just explained all this.