How do you do it without having 5 people FF him? ._.

He either rapes all melee DPS carries from Thornmail & Defensive Curl.

If you have casters, he'll stack HP, get Guardian Angel, and mega magic resist.

Ignore him. If you are a physical dps, stay behind your tanks and out of his taunt range. If you are a caster, snare / stun him to prevent him from taunting your teammates and focus down the enemy squishes. To kill him, you'll need a Last Whisper / Void staff. However, you should not be focusing him in team fights... ever.

He's much softer early game and if you can harass him he has trouble farming up too many tanky items.

I seem to tear through ramus with a last whisperer and bloodrazor. Just make sure you have enough lifesteal to atleast offset his DBC and Thornmail.

like Noth said, Last Whisper rapes Rammus.

Other then that, You can simply ignore him if you have a lot of melee DPS. He isn't that big of a threat, barely any team presence other then his weak-ass ultimate.

He isn't someone to ignore in a team fight, but rather to keep a range from. His ultimate, although seemingly fairly weak, really adds up over time(195/sec/8secs=1560 unreduced, but still, not something to ignore, seeing as he can use his other skills whilst this continues.) and his taunt can effectively take one of your players out of the fight. He is best left to be the last target in your spectrum, however if you have the power to focus him quick without blowing too many of your spells, it can be to your advantage.

Wait until curl is done, then focus fire him if he's still the only good target... if that's the case though, his team sucks.

You don't counter tanks, you get better ones.