>>20642472They are asking you if you have an Arceus to give to them. Its common practice for passerby trades.
I have tons of feebas nicknamed "Yes, No, I don't have it, Sorry no, Only 1 Sory, Give me a shitmon, I dont need that", etc etc
I gen so I gave kids some random perfect iv legendaries sometimes.
Also, most pss notifications just go away if you keep walking or just press B