[okayama]

1st scramble: F2 R2 D B2 L2 D' L2 F2 U R2 D' R' B2 U L' B F2 R' B2 F' D2

1st solution (1-hour): D' B' D B' D' B D B' D' B2 D' B L B' L' D2 B' U B' D B D' B' R U F D U F U2 L' B L F' L (35 moves)

Spoiler (Click to View)

(Inverse)

1st square: L' F L' B' L
2nd square: U2 F' U'
Pseudo 2x2x3 block: D' F' U'
F2L minus 1 slot: R' B D B' D' B U'
Finish F2L: B D2 L B L' B' D2
LL: D' B2 D B D' B' D B D' B D

No good solution was found in time, just a dump solution.

1st solution (after 1-hour): F' L2 U' L' B R' D' L' U2 F2 D R' D2 R U' R' D2 U2 R D' R' U' R U R U' R' U F2 (29 moves)

Spoiler (Click to View)

Pre-scramble: F2

EO + square: F' L2 U' L' B
2x2x2 block: R' D' L'
2x2x3 block: U2 F2
F2L minus 1 slot: U' * R' U R
All but 5 corners: U R U' R' U
Correction: F2

Insert at *: D + R' U2 R D' R' U2 R
Insert at +: U R' D2 R U' R' D2 R

After 2x2x3 block,

F2L minus 1 slot: U2 R' U2 R
More square: U R U' R'
All but 3 corners: U2 R U' R
Correction: F2

leaves 3 corners with 24 moves, which resulted in 30 moves.
Not so difficult, I should have found this in 1-hour.

I'm in a terrible slump currently, and hopefully get a hint to come out of it by participating in this forum competition.

2nd scramble: R' U R F2 B' D' F L2 F U' D R2 F2 U' B2 L2 D' L2 U' F2

2nd solution (1-hour): D2 R D' F2 B R B' R' D2 R2 B2 U' B D B' U B2 D' R' D R D' R D2 L F U2 R' (28 moves)

Spoiler (Click to View)

20 min backup solution.

Pre-scramble: L F U2 R'

2x2x2 block: (ready)
2x2x3 block: D2 R D' F2
Orient edges: B R B' R' D2 R2 B' * D B
All but 3 corners: D' R' D R D' R D2
Correction: L F U2 R'

Insert at *: B' U' B D B' U B D'

Not satisfied yet, but I couldn't find any better solution in time.

For example, instead of the start D2, D' makes a c/e pair, and I searched some continuation preserving the pair.
Premoves L F D' U2 R' and the start F' also looked promising.

3rd scramble: U' F2 D' F2 D2 R2 U' B2 F2 U F' R D R' U' F2 L B L'

3rd solution (1-hour): D B2 R2 U2 B D B2 D F U' L2 U F' B D B D2 B' D R D' R' L B' L B' (26 moves)

Spoiler (Click to View)

(Inverse)
Pre-scramble: U2 R2 B2 D'

2x2x2 block: (ready)
2x2x3 block: B L2
Orient edges: L B L' R D R'
Finish F2L: D' B D2 B' D' B' D2
LL: D2 F U' L2 U F' D' B2 D' B'
Correction: U2 R2 B2 D'

Looks quite a nice scramble, but this was the best I found in time.
Another start on inverse B F2 R2 D2 F' L2 D2 seems interesting.

EDIT: OHHHHHHHHHH, Why did I miss Marcel P's continuation???? Seems so obvious!!!!!