Since there are some people posting their controller layout here, I'll do the same
X: Shoot
△: Usually nothing
O: Focus
▢: Bomb
Select: Trance
Pause: Start
Movement: Analog stick
The reasons why I use the controller instead of a keyboard, are because i can't get past stage 1 on easy without a continue using it, (this is NOT an hyperbole, I'm dead serious) my keyborad sucks anyway, and I grew up playing videogames, so I fel right at home using controllers.
Also, unlike some few people users are insinuating here, using a controller isn't bad, because playing with one doesn't make you any more or less skilled than a keyboard user. I mean really, THIS IS A BLOODY TUTORIAL THREAD, don't put your personal bias in here when it comes in how to play the game. I don't have anything against keyboard users, neither should keyboard users have anything against us.
YES, I do realise it was sort of a joke, but a mean intended joke nonetheless