Probably Wario Land 2. It teaches the player various skills slowly. The player is forced to learn, but it's all natural.
On level 1-1, the player will most likely learn abput invisibilaty. If not, the player will learn about it on level 1-2. In adition to the intriduction to smiwiing, it teaches the player about Flaming Wario, where a Fire Fox (lol, that's what I always called this enemy) sets Wario on fire, and is placed in such a way that it's difficult to avoid - very low coridor, and it starts off chasing after Wario, and there are Flame blocks and water below. Unless the player learns already learned about the Ground Pound move, i dont remember there being a way to avoid the Fire Fox.
Level 1-3 forces the player to learn about Rolling Wario, and more swimming mechanics, as well as picking up enemyes and throwing that (or was that in 1-2? I dont remember clearly).
Level 1-4 teaches the pklayer abpout Flat Wario, by starting the player directly below a squisher. Unless you have a fast reaction, it's hard to avoid. Even the player still thinks that enemy kill you, or has a fast enought reaction to avoid it, you can't complete the level without using Flat Wario.
Fat Wario is introduced in level 2-4.
The treasure and picture panel minigames are simple enought to understand, and they have a tutorial as well. Althought, i would have forced the player to watch the tutorial when they first encounter the minigame. Both tutorials are very short, so I dont think it would be that annoying to watch them every time.
Wario Land 4... That game has 4 passages that the player can do in any order. There is an order of difficulty, but the game doesn't tell it to you. So the player could go into the harderst (was is Ruby or Saphire?) passage first, and it vould get to hard... But still, this game is an option...
Wario Land 3 - i would not recommend the game to player who waven't played Wario Land 2.