For example when A is pressed Nurse Joy will usually ask you if you want to heal your pokemon if the value is 1, whilst the value will always be 0 when you're walking about on the map unless for some particular reason it is set for 1, e.g. you push a boulder down and get the message 'The boulder falls through'.
I was experimenting and found the following codes when searching the value 1 for normal dialogue which displayed text and the value 0 for no text to appear at all:
The interesting thing was that when I left the value as 0 and spoke to Nurse Joy no text dialogue would appear; except a sprite of a man walking back and forth seemed to replace the flashing arrow to continue the text. As expected when the code was set back to 1 Nurse Joy would immediately say 'Welcome to our Pokemon Center' and other lines but when keeping the value on as 1 after Nurse Joy finished healing my Pokemon it appeared that Nurse Joy spoke to me about Pokerus in a glitchy font, even though none of my pokemon had it, I'm guessing this was true because Professor Elm spoke to me about Pokerus when I stepped out the Pokemon Center.
Out of curiosity I set the value as 1 as soon as I walked out of the Pokemon Center, in one instance Bill messaged me telling me that my box was full even though I didn't have any Pokemon in it. On a stranger incidence I set the code as 1 as soon as I walked out of the Pokemon Center and a Yes/No message box popped up with no text to go with it in again 'glitch language', I deactivated the code and selected 'No' and the game did not crash; instead rather strangely the map started to shake and then moved the map view one step down, that glitched up the map a bit and it appears that my character is walking on walls when he is actually one step away from them. I chose 'Yes' later and got the same results.
This time I kept the value on as 1 when talking to an ordinary person in the Pokemon Center, who I presume does not normally have anything 'optional' to say after talking to him normally. But he actually did say something extra! But I can't be certain what he said because it was in that peculiar 'glitch font.' He was a NPC in Blackthorn City, but as I expected a lot of the other NPCs either crashed the game or reset it into a glitch dimension.