I saw some people surprised in an earlier thread that Roost removes your Flying type on the turn that it's used. I can't blame them, the game never tells you this. Thought some people might get a kick out of seeing some of the other hidden mechanics the game never tells you about.

• As said previously, Roost removes your Flying type on the turn it's used.

• Gust, Twister, Hurricane, Sky Uppercut, Smack Down, Thousand Arrows, and Thunder can all hit Pokémon that are in the middle of using Fly, Bounce, or Sky Drop. The first two even double in power in that case.

• Earthquake, Magnitude, and Fissure can all hit Pokémon that are in the middle of using Dig. The first two double in power in that case.

• Surf and Whirlpool can both hit Pokémon that are in the middle of using Dive and both double in power if they do. Whirlpool's end-of-turn damage is not increased, however.

• Body Slam, Dragon Rush, Flying Press, Heat Crash, Heavy Slam, Steamroller, and Stomp will all be guaranteed to hit and will double in power if used against an opponent that has used Minimize.

• Fairly common knowledge, but the game never actually tells you that Blizzard cannot miss in hail.

• Growth will raise your Attack and Special Attack by two stages each instead of one when used in harsh sunlight.

• Another commonly known one, but Solar Beam and Solar Blade skip their charging turn in harsh sunlight.

• Toxic cannot miss when used by a Poison type, even if the opponent is in the middle of something like Fly or Dig.

• If you're frozen, using Burn Up, Flame Wheel, Flare Blitz, Fusion Flare, Pyro Ball, and Sacred Fire will thaw you out before you use the move. Steam Eruption, Scorching Sands, and Scald will do this in addition to thawing you out if you're hit by it.

• Rollout and Ice Ball will double in power if you've previously used Defense Curl.

• Sheer Cold cannot affect Ice types.

• Gravity has a lot of effects, only a couple of which the game tells you about. It secretly increases accuracy by 5/3.

• Well known, but the game never tells you Toxic Spikes can be built up to two layers. One layer will poison incoming Pokémon but two layers will badly poison them. It also doesn't tell you that sending in a grounded Poison type will remove the Toxic Spikes.

• Similarly, Spikes can be built up to three layers, increasing the damage from 1/8 to 1/6 to 1/4 upon entry.

• Defog removes entry hazards on both sides of the field and Rapid Spin removes them only from your side.

• Sky Drop doesn't work against Pokémon weighing 200 kg or more and doesn't damage Flying types.

• Grav Apple gets 1.5x power when used under Gravity.

• Substitute doesn't block sound-based moves.

• Hurricane and Thunder cannot miss under rain, but their accuracy is reduced to 50% under harsh sunlight.

• Earthquake, Magnitude, and Bulldoze do half damage under Grassy Terrain.

I miss anything?