Bronzong
This card redefines the term "nothing special", because it really is the most generic card ever (except maybe for the Poké-Power). 90HP is pretty good for a Stage 1, granted - but not for a Bronzong that's supposed to be Lv.40.
The Poké-Power is pretty good, granted, but you're not likely to discard an Energy card unless you're playing Typhlosion or Blaziken (Bronzong/Typhlosion would be a good prerelease combo, should you get the right cards). Shady Stamp is awfully generic now that Metal Energy are basic, and won't get you near KOing most Pokémon.
The Weakness is pretty bad for a Stage 1, though the Resistance is just above average (for a Metal-type, you should be looking at a -30 Resistance). Retreat Cost is understandable, but by no means good.
Tyranitar
One of my favourite Pokémon. 140HP is excellent, but with a +30 Weakness, you're looking at a probably two-hit KO if you find yourself up against the wrong deck. The Resistance is good, but -30 would be just that bit sweeter (it's a strong Pokémon, after all). The Retreat Cost, however, makes me cringe. I wouldn't dare play this without Switch, and that's saying something.
Payback - brilliant, even if your opponent has more than 1 Prize card left. 40 damage for 2 is great, 80 plus three discard is astonishing. Ground Burn is a little less "wow", though - discarding a card is risky. Would you want to lose something that could potentially be valuable? To me, it'd be worth the 80 damage, but that's your choice.
Best part of the two attacks - add Special Darkness Energy and you're laughing.
Scores
Bronzor: 6/10
Tyranitar: 8/10