This may happen but will be unusual. It is generally bad policy to base an argument upon rare occurences. most of the time the rare occurences do not occur so most of the time the decision looks foolish.
If you never get a particular arrangement because your shuffle technique can never produce such an arrangement then you are not randomising sufficiently.
It is NOT sufficient that you do not look at your deck. Not looking is necessary if you wish to say that what you are doing is shuffling but not looking is not sufficient .
Do you know that your shuffling technique is fully randomizing your deck? You don't. In a truly random scenario, all distribution of cards can happen equally. This isn't the case. Certain distributions are more likely to happen than others. In this case, the deck clearly isn't raondom, but do I know that? No. Do I gain an advantage of certain card distributions not happening? No. Do I gain an advantage for looking at only one card, typically the bottom card, of the deck? No.
In the end, everyone is cheating, because in reality, their decks aren't truly random. What you think, and what actually happens are totally different.
People typically say the best way to shuffle is to do 7 riffles, which is true only for poker decks, but let's just say it is also true for pokemon decks. Due to the law of entropy, the more riffles I do, or in my case, I do mash shuffles, because I can't do riffles, the more random the deck will be. I do 12 mash shuffles, look at the distribution, do 12 more mash shuffles, look at the distribution, and I have been doing it many times, and I can't seem to get certain distributions. Heck, I don't even know if it is a lower probability of getting certain distributions, or if I haven't gotten to certain distributions yet.
In the end, if the deck is "random" enough, it is good enough for me. There is no reason to make a deck fully random when it is impossible to do so.
As I said before, if you shuffle one way, you are more likely to obtain certain distributions of cards, while if you shuffle another way, you get different distributions of cards, and the starting order of your deck does have an affect on what the order of your cards will be after the shuffle.
For example, how many riffles does it take to make the order of your deck exactly the same as the way you found it? In true randomness, there is a chance that the order of your cards will be the same as before you shuffled it. In reality, such things won't happen, unless you riffle it so many times.
In such cases, not looking at your deck is sufficient, why? How can anyone formulate strategies based on the next few cards of their deck if they don't know what the next few cards are?
Maybe they should enact a rule where there is a 30 minute shuffle period, where the person has to shuffle 30 minutes non stop using well known shuffling techniques only, but as we all know, that kind of rule is stupid, and people want to play, not shuffle. In the end, people do all this declumping, or sorting, or what not, is because their shuffling technique is bad, and they seem to get unfavorable distributions of cards every time, in which case, their deck is random, no matter how favorable the distribution is. It would take them much much longer do do their way of shuffling.
Now do you think this method of shuffling is cheating?
You take a deck, and cut it around the middle, so you have 2 piles. You will also need a dice for this.
You roll the dice, and whatever number it lands on, you take that many cards from the top of the first pile, and place it as a new pile. You roll again, and do the same thing as the other pile, and place the cards on top of the third pile until the cards in one pile run out. If there are no more cards on one pile, you put the rest of the cards, without reordering the remaining pile, and place that on top. You split your deck near the middle again. You repeat the procedure 7 to 12 times.
If someone would see this, they would no doubt call this cheating, but the way you are placing the cards is no different from a certain shuffling technique you know and love, just more time consuming. The one difference is that one way is super slow, and easy to keep track of which cards end up being which, while the other way is fast, and is harder to keep track of which card is which, even though the outcome will end up being the same.
If you want true randomness, throw your deck in the air, and with a light blocking blindfold, pick up all the cards and place them in a pile, and get the judge to make sure all the cards are oriented the correct way. True randomness.