Do not worry Bibs, Normal cannot function without a mega (and imo needs Meloetta), so it's probably higher up. Normally you'll see types without legendaries (like Poison) or without the need for a mega (like Water, Ground and Dark) in the first places, especially if you want to make this hard.
At the same time you have one-dimentional types like Electric, which may be in the first spots as well, since they can't make use of legends either.
Even with Electivire they still have a long way to go. However, I stay a bit skeptical since M-Ampharos is a thing that would benefit the electrics and is a shame not to be in the team.
Grass is going to be way too easy to start with, being deprived of megas (yes even with Cradily, Ludicolo, Roserade and Ferrothorn), so they'd probably want to buff it up to the positions where you can use a mega (M-Venu or M-Sceptile are very good options) as things like Celebi and Shaymin aren't allowed.
For the same reasons with Normal I would exclude Fire, Ice, Fighting, Bug, Fairy, and Rock
I do not think they would go so far as to remove Dragon's potential early on (aka M-Altaria), so my guesses are:
edit: Right now I am very curious about the pokemon the Psychic leader will use.