So technically there are 41 playable characters total?
Yes. But as shinpichu said,
technically 42 if you count Nana.
But for intents and purposes, they count together.
Notably, Giga Bowser doesn't freeze up when you end the game with him(he has a results screen). I think his leftover data from Melee could be the cause of this. He also has a lot of extra unused data.
Him not freezing the game at the results screen has
nothing to do with Melee.
Or did you forget that Giga Bowser has no result screen data there?
And that extra unused data also includes animations only present in Brawl's Giga Bowser such as Assist Trophy summoning, clapping (he didn't have this animation in Melee), etc.
So no, the data was clearly copied from
Brawl's Bowser and tweaked to produce different effects.