A theory and sort of prediction on how Nintendo will do the Arms Character reveal, a thread:

Basically the video reveal will begin where we left off Incineroar in his reveal. Fighting off characters in a free for all.

Incineroar beats off all the remaining characters and believes he's victorious, until...

Now, with all the chants in the background and the "oh oh oh ohs" from the Arms Main theme, it is now time for your new character. Yep, it's the Arms rep (using Spring Man here cause he has the most material I can work with)
The music will also sync with the action in the screen

Video acts like the Ken half of Incineroar's trailer where we sort of expected the Arms rep already and is showing a bunch of clips of the Arms rep in action.

We then see some CGI choreography of Arms vs Incineroar. While this is happening, a mysterious figure steps into the background.

Yeah it's Incine's turn to bite the dust in the KO screen. But, just as the Arm's rep pops off over this victory, we see a "NEW CHALLENGER APPROACHING!!" in the background. Who could it be?

The figure from before enters the ring!

It's Sol Badguy from Guilty Gear!

With "Smell of the Game" playing loudly in the background starting with "I KNOW WHO I AM"

Mainly picked Sol here as he's another Fighting Game character and would fit in along with the Arms reps, which is technically a fighting game character.

Video ends with "WE KNOW THE SMELL OF THE GAME"

Oh yeah, and the Arms rep falls out too.

With that, the video closes with the two new revealed characters with their dates. Sol is shown first to be for Fall, while the Arms rep is OUT NOW! (at June whenever, probably the weekend of June 11th)

When it comes to the Sakurai let's play later that day, the Mii Fighters that'll come along with Arms will also be discussed. Because it's a Nintendo rep, the costumes will be all over the place like it was with Banjo and Byleth.

This another special Mii costume like sans.

My dibs are on a Freddy Fazbear Mii Costume or even a Geno Mii Costume for this pack.

And that's all that I wanted to discuss!

Is Sol Badguy likely? Probably not, but it was fun to think about.

Anyways, if the Arms rep reveal doesn't take place in the Boxing Arena, that'll be a missed opportunity if they decide to reveal two fighters in one day.

They will reveal two fighters in one day though, since the reveal is supposed to take place during E3 times, they did reveled two sets of characters in E3 before after all, twice.

I'm confident.

Alright, that's all the stuff I wanted to discuss as I've been thinking about this for a while.

I got to get back to playing Animal Crossing New Horizons on my Nintendo Switch.