looks like we got another one who was expecting the SNES version. the Arcade version didn't have a manual dash either, and also throws and slams were random in that version. i'd bet getting in a lock was an Arcade thing too.
for double jump, you have to doubletap the jump button very quickly.
I wasn't expecting the SNES version, but you think they'd tweak some archaic controls? Thankfully, I've either figured them out, or found workarounds:
Manual Dash - Okay actually, no, this is just inane. I don't have a workaround for this except the Special Attack, and that still doesn't give you REAL distance unless you're using Donatello.
Throws and slams - Should be an input. It's strategic. Yeah, you've got screen clearing power, but only on two axes. Use it wisely, or else you'll be open to attack from 2-6 other directions.
Locked - This is an ancient arcade tactic, and should have been fixed, but fortunately it only really kicks in when there are Rock Soldiers or THOSE BLASTED HELIFOOTS. Again, Donatello.
Double Jump - You can only do this at the height of your jump? Pffft. What a load.