So I understand they can be played in other roles, but one normally sees Alistar and Blitz as support so why doesnt Riot classify them as supports? Even if its considered their secondary role, they should be classified as such, like Leona is.
Alistar is an AD bruiser: 
-> Irelia 2.0
Blitz is either an AD assassin: 
or AP assassin: 
/
No, they are not supports
I have literally only seen AD alistar once.
Major terminology confusion in the community: just because someone assists in bottom lane doesn't actually make them a support. Same reason AD Zilean or Crittlesticks aren't suddenly marksmen.
Supports are champs that sacrifice some of their own power for the team. (heal, shield, buff)
Leona is only classified as Support, because of her passive. It boosts allied damage, but does nothing for herself.
Alistar's AoE heal is not a support abbility because it benefits himself more than the team.
Blitzcrank has no team abbility at all.
