One thing I noticed, though, is that when Mark was looking for his pokemon, he is carrying 7: Charizard, Jolteon, Letaligon, Sandslash, Dragonite, Scyther, and Gyarados.
Mm, not exactly. You're presumably talking about when he stands up to go look for the dragons in the evening, but at that point he explicitly does
not have Gyarados out; though he sends Gyarados out a little later, he's never after that point mentioned to still have everyone else out (or I don't think so, anyway), so there's an implicit switch there. Maybe it should be explicit, but there are never explicitly seven Pokémon out at once, either.