My Masters Of Evil:
Temugin:
Tactician, master planner, master martial artist able to tear apart Iron Man through using chi force to enhance his strength, durability, speed and reflexes.Temugin with his rings owned IM so bad it wasn't even a fight, same without them.
He's worth of being son of the Mandarin and probably superior to his father.Also the rings are magical in nature.And there's some guy in the JLA who doesn't like it at all...
Absorbing Man:
Creel is sometimes portrayed as an idiot, absorbing glass or simple wood.But when he use his powers in the right way, like absorbing Mjolnir's capabilities, becaming hella strong and durable, he's really badass.Even just absorbing steel or titanium he goes into Class 100 and not on a low ranking, he throwed down with Thor many times, he even absorbed energy from the Earth Core.Leaded from Temugin, he'll be a real trouble for the JLA.
Radioactive Man:
Yeah now he's with the good guys, but in the old days, he was one of Thor's enemies, and a tough one.He can enhanced his physical abilities to high superhuman level, emit radioactive or nuclear energy, heat blasts sufficient to destroy a whole city block on a whim, force field able to repel Mjolnir itself, and he's also a genious.
Juggernaut:
No one of the MOE leaders ever tought about hiring Cain.They always contacted loosers or mid-low level metahumans, while around in the USA there was the UNSTOPPABLE JUGGERNAUT!
Mangog:
One the Asgardian greatest foes, his physical powers are something even beings like Thor, BRB or Odin consider a threat, not to forget his
ability to manipulate magical energies.
Graviton(at the power level he was when he fought the Thunderbolts on his flying island)
He's one of the greatest team wrecker, only excessive self confidence makes him beatable.
JLA Roster:
Superman
Wonder Woman
Aquaman
GL Guy Gardner
Firestorm
Red Tornado
That's why I sayed it's Graviton at the level he was against the T-Bolts in the fight on his "Sky Island".RM yes known the Kryptonite Wavelenght, but this doesn't means SM is screwed.Dont' forget there are Firestorm and RT on the JLA roster, not to mention Guy Gardner.
Wasent on Thunderbolts where he did suspend everyone up in the air? Even if his lower hes still a nasty team wrecker. And you still have Mangog there, thats way up for SM and others to tackle. And Juggernaut. The villain team is just that uber.
The ones in the JLA team that can give some headaches to some of the first, are Gardner and Firestorm i think.
RM has force fields which can protect him from most form of injuries or attacks, Firestorm isn't something he can't handle, RM is not just some idiot who got powerful, he's a genious in physics and so.It means he knows very well how his powers works and how to use them in the best way.Also AM abilities are magical in nature, dunno if FS powers can overcome Asgardian Magic.
Firestorm can just the convert Radioactive Man's nuclear energy into cotton candy...literally. Firestorm can also just absorb every last bit of RM until he's nothing but fizzle.
Firestorm's connected to the Quantum Field so his energy absorption is literally infinite.
Absorbing Man absorbs whatever he touchs....and Firestorm simply makes him turn into plastic.