What is the minimal cp raid team for machamp?

There is no strict answer to this. More than attacker's CP, the outcome of the raid depends on:
* Machamp's attacks
* Machamp's weather boost
* Attackers attacks
* Combination of attackers IVs and levels, which can be approximated with CP

I recommend using GoBattleSim (https://pokemongo.gamepress.gg/gobattlesim) which I have used a lot myself for Machamp raids. You can fill in your team and then try to see which level they need to be in order to defeat Machamp.

That being said, I think 5 Espeons make your team too frail to prey on Machamp with a charge move other than Close Combat. You need to add pokemon with more survivability. Alternatively, if you have a good phone, you can try to heal your Espeons when they are all fainted and then send them to battle again, in which case they are good candidates because of their high DPS.

at least L30...
Your team is good but you need some dodging strategy to avoid being wiped out...
Your roster are good for pure Fighting Machamp Boss... I think you got trouble with Bullet Punch + Heavy Slam set since Steel are Psychic's Weakness...

I hope it help... Good Luck Bro and Play safe always...

To start with, asking for a CP is wrong. CP is an useless indicator of your pokemon strength. What determines your pokemon strength is its level, individual values (IVs) and its attacks (fast and charged). Mewtwo with psiquic moves is viable at level 25 for example.
Machamp is a relatively easy solo with level 30 pokemon. Espeon has good DPS Vs machamp, but it's a bit frail.

You have a guide to solo Machamp un this website with videos included.

Short answer, 2500-2600ish is fine