For achievements, changing any options is permitted, including life count and score extends.StarCreator wrote:"Difficulty"? If you mean Novice on/off, probably. If you've been mucking with the settings, changing any of those from the defaults usually disqualifies you from every achievement in the game.
The 1cc achievements can't be done in Novice, though, nor can the Shin mode TLB one. The no-form-change 1cc can be done in Novice.