SMW2 tricks

Major tricks (15 sec+)
1-2 SIMPLE skip on screen 2
2-1 1-1 warp
2-2 various skips
2-4 gatehack & 1-1 warp
3-8 boss 1-shot kill. Also know ghost skip in 2nd sewer area.
6-4 various skips
6-5 2nd autoscroll skip
6-6 keys early
6-8 door 4 everytime

Moderate tricks (5-15 sec)
1-8 salvo kill
2-7 cannon despawn
3-4 spike jumps
3-6 alternate route
4-4 arrow skip in lower right room
4-5 extended flutters over poles
4-7 1-1 warp
4-8 breakable block skips
5-2 ski lift skip
5-3 various skips
5-7 piranha skip (dangerous)
6-7 know where to fall on screen 2

Minor tricks (1-5 sec)
1-1 beanstalk skip
1-4 pot break
1-6 beanstalk skip
1-8 platform manipulation & arrow blocks
2-5 shell jump & cloud use
3-1 1-1 warp
4-1 baby mario star early
5-1 cloud rides
5-4 skip spikes by hopping off slime
6-2 baby mario final star skip

Levels recommended to practice heavily, regardless of skips:
2-3
3-2
4-1
4-3
4-4
5-1
5-3
5-7
6-2
6-4

1-2 skip isn't worth practicing until world 2 times are consistently below 31 minutes or so.
5-4 autoscroller skip is essentially impossible on console.
6-4 lava skip only saves 3-4 seconds. !! TrY aT yOuR oWn RiSk !!