SONIC THE HEDGEHOG

You need an S ranking on every act in the Shadow episode--normal, hard, and boss battles included. In the ACT levels, getting 50000 points or above gets you the S. In a boss battle, you only need 30000-10000 of which are awarded for defeating the boss.

As a general rule, you don't need too large of a time bonus, usually only around 15000, just complete the level without dying and killing basically everything along the way, especially the enemies worth 1000 points a piece. Go for enemy combos as well. Rings aren't as important as in the Sonic stages, you can typically S a stage without any ring bonus at all.

Level-by-level extra help:
---------------------------
White Acropolis
-Destroy the searchlights as Rouge by tossing bombs at them--1000 points a piece.
-On normal difficulty, right before you take the warp into the base in the first part as Shadow, there's a huge group of the small robots--kill the red one for up to 7100 bonus points.
---------------------------
Kingdom Valley
-Hit all the rainbow rings
-Try to kill all the huge 1000 point enemies as rouge, there are a lot of them and you can get up to around 16000 before Shadow's hovercraft part
-This one is a little tight, so try and get a descent time bonus
---------------------------
Crisis City
-Don't bother with the buggy and just kill all the Giants and Grabboid monsters for 1000 and 300 points a piece while running along.
-1 rainbow ring at the end of the second area's rail portion. There is also a 4600 rainbow ring combo on normal difficulty only in the final third of the level right after you pass a buggy(in the "End of the World" level, this part is the second half of Tails' portion)--hard to miss.
-Plenty of enemies on hard difficulty.
---------------------------
Flame Core
-Don't die.
-Hit the rainbow ring near the start.
-You can kill basically everything in the Rouge portion and get a free 8000-9000 points for doing so.
-Plenty of Giants and grabboids to kill--you should be able to get around 22000 before entering the volcano.
-Don't die
---------------------------
Radical train
-Time Bonus Necessary. You should aim for a time bonus of around 30000 or more--mine was 37000 and I limped by.
-Hold onto rings if you can--less stressful that way because you can afford a smaller time bonus.
-Only kill big enemies or enemies in your way--remember to keep time.
---------------------------
Aquatic base
-Super easy, just kill everything in your way and you'll get it no problem.
-When possible, activate the blue magnetic pillars to kill enemies for huge bonuses
---------------------------
Wave Ocean
-Also Super easy, you can get over 10000 points from the glider section alone, then kill everything in your path.
---------------------------
Dusty Desert
-Get through the hovercraft part as fast as possible.
-Kill everything in your path except for the big "sand-waves rooms", where you should only go for the ones in your way and the giants.
-Aim for a time bonus of around 19000 or so and you will make it if you have killed a lot of badnicks.