Here are some day 1 combos for Rain that I was able to do. Some are a bit similar to each other, but whatever. I'll add notations soon.
Combo 1 (0:00):
1, 2, f4, dash, 1, 2, f4, dash, 43 ~df3, 2 ~db2, dash, db4, db1
Combo 2 (0:12):
43 ~db2, 43 ~db3, 43 ~db3, 3 ~db3
Combo 3 (00:22):
b2 1+2, dash, 43 ~df3 (aim bubble above head), 43 ~db2, 43 ~bf1
Combo 4 (00:35):
jp b2 1+2, dash, b2 1+2, dash, 43 ~db2, dash, db4, 4 ~df3
Combo 5 (00:45):
43 ~db3, step forward, 43 ~db4, 4 ~XRAY, 3 ~bf1
Combo 6 (1:00):
1, 2, f4, dash, 43 ~df3, (aim bubble above head), 43 ~db2, 43 ~bf1
Combo 7 (1:12)
b2 1+2, 43 ~db4, 43 ~db2, dash, 1 ~bf1
Combo 8 (1:22)
43 ~XRAY, 1, dash, 1 ~db3
Combo 9 (1:35)
jp 1, 2, f4, dash, 1, 2, f4, dash, 43 ~db2, db4, d4
(1:46) = bad ass pose
Key:
1 = front punch
2 = back punch
3 = front kick
4 = back kick
f = forward
jp = jump punch
d = down
b = back
u = up