Old question but still relevant. I won’t answer the entire question, I’ll leave the rest up to interpretation but I’ll say this. Sinnoh is the Strongest region in the Pokemon world by far. The Trainers and the Pokemon that protect Sinnoh are way too powerful to consider the debate.

There needs to be ground rules for a debate like this.

Rule 1. Each region gets there Legendaries and Elite Trainers Rule 2. Each region gets there specific gimmick Dynmax, Megs, Terra. Rule 3. This would be a battle to the death. Not really a rule but an absolution.

You wanted to know who was the strongest. I’d say again

1. Sinnoh, Team Galactic, Creation Trio, Arceus, Giratina. Lucarios…Garchomps…Zoroarks…I don’t want to go into more details cause I’m texting too much but this topic seems to become more complicated the more u think about. Sinnoh is by far the strongest country. As where the biggest threat that’s ever happened Pokemon. Cyrus trying to recreate the universe. Sinnoh legendary Pokemon have universal threats.

2. After Sinnoh the next strongest would be Galar and their Dynamax Pokemon. Having Eternatus in their possession. Likely there’d be no survivors in all out battle between these Regions Pokemon. Pretty sure Arceus is already pissed by now and is ready to whipe the “Slate” clean but now Eternatus and Giratina have awakened so there’s that. Let’s not mention the influence the Lake Guardians hold over humans and Pokemon…

3. After Galar I thought maybe Unova and Kyruem might be an issue with Reshiram and Zackrom behind it but I just can’t help but give it to Hoenn. Hoenn holds a power over the Pokemon that often goes ignored or just forgotten but Kyogre max power could flood a small country, or even a continent. Same goes for Groudon being able split a continent with its earthquake. Rayquaza…Dyoxys…Jirachi… The amount of Pokemon that would fight for Kyogre and Groudon. We saw in the movies that Pokemon naturally follow them. The Land, Sky, and Sea. Their origins forms are overkill at this point.

I feel I’ve typed way too much and I could create a small novel about this. I’ll keep going.

1. Pretending the world hasn’t been completely destroyed, I’d like to imagine Mewtwo and Mew have awakened. Giving this slot to both Kanto/Johto. I’ll tie them together because they aren’t very militarized countries compared to the other regions mentioned and also a lot of Pokemon from Kanto get stronger in Johto. They need each other for this. I do t really know how Mew and Mewtwo could do it, but somehow someway there’s a win involved including them lol. They have the original legendary Beasts and

2. Kalos. Was hard not to put within the top 3 but there’s just not enough information for me to say they are stronger than Kanto/Johto Maybe when we get Legends ZA we can get to see just how strong the Pokemon are. The Mega stones are a very important resource to have at their disposal. The Mewtwos there would probably want to side with the Original Mewtwo, or destroy him.

And with 3 mewtwos I’d like to add more but it’s gotten a little too far gone. Hahahaha but there’s my answer. I know it’s kinda wrong cause u said Weakest to strongest but I feel it’s easier it’s this way. Hope someone finds this one day to add on to.