I used to play through Valis II again and again without dying with no tricks back in the day.
There was no internet, so unless I came across a trick in a magazine, I never even heard of them.
Valis II is easy enough if you practice. Valis III is also easy except for the last level and or boss if I remember correctly.
By easy, I mean you play it a bunch of times and can get good at it.
They're not those kinda games where you have to memorize everything to make it through nor are they the kind of games that you can pick up and play through in one sitting either.