Figured I'd at least start on this one, it's one of the most well known PCE games.
Heres a small wip up to the beginning of stage 2:
http://www.teamspooky.com/TAS/keithcouragewip1Sp00ky.zip
Early conclusions:
The gunhead enemies are extremely useful for damage boosting. In fact they could be used in more places than I showed here.
The Areas where you play as Keith are going to be a pain. He's slow, he doesn't have the damage boost tricks he does in the alpha suit, and manipulating enemies to drop coins may be tricky. Also the hitbox on his sword isn't good enough to hit enemies on the way up from a jump, and ground slashes stop your momentum.
In my opinion only 2 of the sword upgrades should be collected, the 2 that extend the length of your sword. This will help with coin issues.
Hearts do need to be collected at some point. Damage boosting off enemies is really useful. I'm not sure what enemies will be the best source of hearts.
The gunhead enemies need quite a few hits to die (and are our main source of damage boost which means often we don't want to kill them). The ninja-robot bomber things might be a better choice. Some later bosses can probably be killed faster if we can attrition them and just trade damage until we win.
The final boss has a well known trick where if you jump into his area at the proper angle he is unable to move, making him trivial. Another kind of well known trick involves falling into a spike trap at a certain angle, this will allow you to be able to walk amongst the spikes safely (you cannot jump however, you must fall out of the spike pit to another ledge to escape safely)
Things that would be most valuable, in order:
'Fall through floors trick': This would be an awesome find as it would make the Alpha Suit stages extremely fast. I tried having enemies push me through small gaps and such but to no avail.
Ways to surpass speed limit: Keith especially would benefit from this as he is really unbearably slow.
Coin/Heart manipulation ideas: I'm not 100% sure yet what influences enemies to drop items.
Would love to hear any other ideas or see any other WIPs floating around.