Singed is the best IMO. Good luck getting to play him in ranked.

Voli is a good sub choice provided you are not in need of AP.

Rammus ganks like a baws.

Shen has is a great support tank with OK damage output.

Mundo. Get's out of control middle to late game and is extremely hard to take down with only 3 players, even with ignites.

You might think It's strange that I am commenting to your answer when I don't own Nautilus myself(mainly because he is a 6300 IP champ). I have researched nautilus and correct me if I'm wrong but I've heard he really is a good tank but I also heard that he is only as good as the team he is playing with. What I mean to say is that he really isn't a champion that can solo as well as others but instead depends more on players working together, when that happens then you might see an improvement in Nautilus's viability. But with a bad team his viability slumps off.

i've never lost with him but in my opinion its nautilus, his Q grapples and stuns for a short period of time. his Passive stuns he has 2 slows, 1 knock up. his damage output is incredibly huge. and he can seriously take hits. his W more hp= more damage he does+ more damage he can reduce, hes seriously the best champion in an overall rating i've ever used. and seeing as i've never lost with him im pretty sure others should try him out.

incorrect, i've carried, and solo'd 3v3 and 5v5 using nautilus, engaging enemy team and completely scattering there efforts, and in most cases killing most of them off. hes very offensive and defensive character in my opinion hes the perfect character, the way his skills are, hes almost or in my way, hes unkillable.

Singed, Malphite, Shen.

haaaaaaaaaaaa

Volibear.

Armor+Bear.

What do you think is the result?

In my opinion any champ with a good pull like blitz and singed so you can easily feed your team and turret/spawn spank. Always successful

I play Mundo as a tank on 3v3 and mid to late game he is unstoppable if you build right. Play defensively early on, try to go top and harass while getting a large far (as well as a heart of gold for money) and you can build to counter whatever team comp they have. Run movement quints and ghost and even if you are hurting in a fight you can pop your ult, then ghost and no one can catch you...I sometimes pick a 3v1 fight late game, kill one champ and then pop my ult and run away allowing my teamates to backdoor or push lane. Most folks do not realize how fast a good mundo can run.

Part of it is dependent upon your team however I do feel that Leona is 1 of the best for T T