I think that Articuno was not supposed to exist, and Ho-oh was supposed be in its place. The legendary trios (birds, dogs, regis) are based on a Chinese mythology about the Phoenix, Cat, Tortoise, and Dragon. Phoenix? Ho-oh? Ho-oh was supposed to be part of the 3 birds, and was supposed to be their leader, IMO. Articuno is the first of the three (uno), which proves that if Ho-oh was in its place hecould easily to be the leader. The Articuno picture on the wall looks more like Ho-oh than Articuno. Look at its tail. Articuno has one single tail, not one that spreads out. The picture on the wall of the pokemon center has a tail similar to Ho-ohs.
Also Zapdos's picture is green. Wtf.
Even more, why the heck is Arcanine there? I guess they wanted Arcanine to be a real legendary.
So from this episode we can gather that Articuno was not supposed to exist, and Ho-oh was supposed to be in its place. Zapdos might have been a grass type? Lmfao. And Arcanine was supposed to be a real legendary.