[What OU 'mon I think each member is]

I'm very interested to see what you come up with

[Make your own Pokemon moves and comment on others.]

Well this could be said as a slightly better version of hurricane but also slightly worse

Cyclone: 90 Power 90 Accuracy

The user wraps the target in a raging whirlwind

has a 30% chance to confuse and has a high critical hit ratio

Users: mostly flying types

the only way to get it is through move tutor

[What's the hardest game you've ever played?]

Call of Duty Black Ops 2 on veteran difficulty it was rage inducing but it was worth the achievements

[If you could own one Pokemon, what would it be?]

hmmm... maybe Delphox or Lucario

[Name up to 3 pokemons you're going to use to face Reborn's champion.]

Milotic because it can tank special and physical attacks if EV trained with the ability marvel scale as well

Lucario because fairy types are a thing and it can bbe ran as a mixed attacker

and Darmanitan because sheer force attacks can hit like a truck

[Starter..?]

Well with the first gym you'll have lots of issues with tentacool and tailow because of Julia. If that's what you're looking for go ahead, in the end Tailow would probably the least useful of the 3 late game, in my opinion

true but then there was julia's emolga being a problem for breloom but i don't know if it had a flying move to begin with.

[Starter..?]

Normally I would say go with what you like but it all depends on what they're advantages and disadvantages are. What I suggest is to look over the gyms and the weaknesses of the starters first before anything else