Question about size

Hi, I've been searching for a while but I can't get a good answer to my question from Google or reddit so I wanted to make a post in case someone here can help me

I hunter for shiny Dragonite a while ago, and I got it, a small green dragon, but recently I also got an alpha one from area 20 randomly and I've been doubting what to do

I love my two Dragonite and planned to use one as a physical attacker and the other one as physical one, but I'm doubting which to make physical and which to make special

I've heard smaller Pokemon are better as special attackers because sometimes big ones can't aim properly to enemies that are close, but idk if that's the case because I've also heard alphas are good because they have bigger beams and bigger hitboxes

So that's basically my question. Which Dragonite should be physical and which one special? Are alphas better as physical attackers or special attackers?

If anyone could help me I'd be very grateful, thanks in advance