Weirdness. Yesterday when I tried the catching challenge all I could find was Pikipek, Yungoos, and the occasional Rockruff. No Pikachu at all in like 30 encounters. Today, when I tried it again, I find Pikachu with Pikipek and Rockruff. No Yungoos at all, even though they were the most common yesterday.
Is there a code in the demo that governs the rarity of the Pokemon in the same area depending on the date or other variables? This is very bizarre.
EDIT: And seriously, now it is just a swarm of Pikachu in the grass. Is it a case of "when it rains, it pours", or is there some sort of coding in the demo that allowed this to happen?