First Teammate plays cho or amumu or teemo

I play Yorick, Udyr, Riven, Rammus, ww, cassiopia.

Other guy plays- GP, Rumble, singed, kennen, shyv, olaf

Based on those champs what would be the best comp?
We ban mundo tryn lee.

I'm thinking we put cho bot Rumble/singed top solo and I jungle.
Or udyr bot solo amumu top solo and gp/shyv/olaf jungle

With the options you listed... I like Cho bot, Riven jungle, Rumble top.

However, "First Teammate" is kind of limiting your team. You and "Other guy" both play a lot of viable champions, but Teemo is situational, Amumu is mostly a bad pick for TT, and Cho is good, but not as good as some other strong APs. Try to get "First Teammate" to learn some more champions that are good on TT.

Also, pro tip for banning: If you plan on banning Trynd no matter what (which I don't think is necessary, but anyway...), wait until your last ban. Lots of teams will ban Trynd. If the other team bans him before you do, you get to use a ban on something else instead.

Yeah, first teammate is killing you here. Amumu and teemo, not so viable in my opinion, chogath can be good but that relies heavily on his skill level.
So you and the third player are possible jungles, shyv,ww,riven,udyr. Amumu solo top won't win vs anyone halfway decent. I have really noticed a lot of amumu picks whenever I play on a smurf or start a new ranked team, I seriously count it as a free win.
Your possible 1v2 lanes are yorick/singed/rumble, top lanes are olaf/gp/udyr/riven/cass/cho, bot solo 1v1 are ww/cass/kennen/singed/rumble/teemo.
Try not to run yorick/kennen/teemo/ww on the same team, it will get you killed early game since they have essentially no ability to move around 1-5.
Banning trynd is dumb, mundo probably isn't worth the ban, lee is understandable.

Thanks so much, we will give Rumble, Riven, Cho a try. So if you guys don't ban mundo or tryn who do you see as a threat besides singed.

shen/lee/riven/cass/singed are normally what I think are priority bans, a lot of the ad melee can be considered here as well, including some other strong junglers like shyvanna. Mundo could be a good ban, but usually I think it isn't too hard to counter him. If you have a team comp in mind then try to think of bans that would stop your team from being countered. With riven/rumble/cho you have a really tanky team that is decently mobile with pretty good aoe cc. As long as you don't split up in the endgame teamfights should be easy. Teams that might counter would be strong slows and area control with ranged dps.
That's my immediate thoughts anyway, talk it out with your team to see if any of them have a specific champ that they normally lose to.

Singed will be banned every game, I would be surprised if you would be able to pick him.
Cho'Gath is a SOLID champion on TT, Tier 1/2 easily.
Udyr/Riven/GP/Shyvana/Olaf are all great tanky-DPS with survivability and big damage output.

I'm likin' the looks of:

Teemo/Udyr/GP - Fight the battle on your terms in the jungle
Cho'Gath/Riven/Rumble - Some good AoE and CC

Our cho player will be taking some time to learn a new champion and I will be focusing on jungling along with ward placement and getting everyone to ward.
Gonna play some normals and see if we can get another champion or 2 in the rotation from our cho player.
Any suggestions for her?

Have her learn some of the champs that you and "other guy" know. Between you and "other guy", you can create quite a few viable teams.

GP top, Singed top, Olaf top, Riven top, Udyr Top
Riven Jungle, Shyv Jungle, Olaf jungle, Udyr Jungle
Rumble Bot, Kennen Bot, Cass Bot, Singed Bot

Those can all be mixed and matches to, in general, create effective teams, so if she could learn one or two of those, your group would have an easy time making a team.

If you want some variety, I notice nobody in your team claims to know Renekton or Lee, both strong picks in most cases. She could learn them.