This is a comparison of all 3 consoles in their first 4 months. Wii U sold 3.45 million units, while the Switch destroyed it with 4.7 million. And this is with Wii U having the "holiday" advantage. On the other hand, the original Wii bested the Switch with 5.84 million units. An impressive accomplishment indeed. So the Switch does not appear to be on track to match Wii. However, let us analize the situations. 

Both were in shortage situations, artificially manufactured shortages or not. Both were somewhat similarly priced if you adjust for inflation. However, I would put Switch at a bit more expensive considering no game came with it and a pro controller costs more. 

Wii was released late in the year. Switch did not have that advantage. Wii had a pack in game. This would appear to give Wii an advantage over Switch. Wii also had a successful new gimmick (motion controls) to propel it's sales. On the other hand, Switch was launched alongside The legend of Zelda: Breath of the Wild. That is one of the highest rated games of all time. In the top 5, in fact. Wii had no huge seller like this at launch. It had a lesser Zelda game: Twighlight Princess. Switch also has the new portable/home console factor.

So which is the bigger success in it's first 4 months? I think it's hard to say. I think the strongest indicator will be the one year sold totals. If I had to say which would do the best at years end, I'd give it to Wii. Because Switch has been consistently given more big titles than Wii so far, I think, yet Wii is winning. What do you guys think? Will Switch switch it up by it's first year of sales and outsell Wii in it's first year or will Wii whip Switch's hind end? 

It depends how many Nintendo will produce. It could have easily beaten the Wii without supply issues.

But will it be able to catch up to the Wii once supply meets demand?

Twilight princess a lesser game? Hmmm I'm not sure that game was hyped up big time and delivered.

So in other words the Switch is running faster than a snail but slower than a rabbit.

The Wii was a once a generation thing. I doubt Switch will do better. When it is all said and done the Switch will outsell the Wii but not in the first four years. I say this due to more 1st party support and longer lifespan.

Remember, Wii had major supply issues for at least a year. Or if you are too young to remember, look it up. 

Exactly.

Yes, but not in comparison to BoTW. I don't think I've ever seen a game so hyped while getting great reviews.

If Nintendo can keep the big games coming at this pace, you may be right. 

Let's analyze the situation even a bit further: Switch stock is suffering perhaps even greater shortages than Wii did in key areas, and Wii released around the holidays. You're comparing a system released in March with one released around the prime time of console sales. People keep forgetting this crucial fact. Switch doing this well from march and up is pretty insane. 

Nintendo is directly competing for parts with Apple and others as well, Wii didn't have this issue to my knowledge. Nothing near on Apples popularity anyway, which gives Apple priority over Nintendo in getting those parts. That's why I believe the stock situation is even worse for Switch right now. 

When you look at the full picture, Switch may have even more appeal strength than the Wii potentially (not for certain in the long run, but possible) That isn't too far fetched either, as Nintendo handhelds have always/usually had close to or even greater appeal than even the Wii did. The main hurdle for Nintendo is whether or not they can meet demand before people lose interest.