I've been quite surprised by some of the stuff I've found.
So far:>Gen 1
Charizard: Not OU tiered. Wasn't terrible as Fire-types go, but none of them were good enough to even have a niche in OU. Gen 1 UU is not a good place for it either since Tentacruel runs it with an iron fist.>Gen 2
Charizard: UUBL. High risk, high reward. Ranked 29th(C2 Rank) on the OU Viability list. Not great, but not bad. Highest ranked fire-type(Moltres is 30).
Typhlosion: One of the worst mons in the same tier, at Rank 55/60(E2 Rank).>Gen 3
Charizard: UUBL. Still high risk, high reward. Surprisingly the highest ranked of the three Fire starters(D1 Rank). Second best Fire-type in the tier behind Moltres.
Typhlosion: UUBL. Not even on the viability ranking, which doesn't bode well.
Blaziken: UUBL. More immediate power than Zard, but slower. Ranked D3 on the current viability ranking.>Gen 4
Charizard: NU. Generally considered the best mon in the tier.
Typhlosion: NU. Eruption finally arrives. Typhlosion is very good in this tier(A Rank) and is considered quite dangerous, but not quite on par with Charizard or Magmortar. Good Choice Item user.
Blaziken: UU. Great wallbreaker in the tier and at A Rank in the viability list for this tier. Not the highest ranked Fire Type in the tier though(Moltres and Arcanine are S Rank).
Infernape: OU. Used to be considered one of the best mon in the tier, but is struggling at the moment. Is holding an A+ Rank(More or less Top 10) in the viability ranking, but most people in that thread want to move it all the way down into B+(Barely Top 30).