Rate my team: 1.venusaur lvl.70 Strength Frenzy plant Solarbeam Razor..

Venusuar- too much grass moves, maybe learn sleep powder
Umbreon- take mean look for psychic, then you would be killer
Espeon- cut=no, get it deleted and learn it return or some other stronger normal attack, cut is a little weak for the big leauge
Mewtwo- good, but could be better if you take swift for recover, any Pokemon is good if it knows a recover type attack
Dragonite- rock smash=no as well, get it deleted for something else, like dragon claw, etc., fly is a little bad on dragonite too, you could take it off and put aerial ace, still a flying attack but better cause it only takes one turn and never misses if they are there
Cacnea- can't really tell you since it's in training, just make it know ingrain in a few levels, faint attack, neddlearm, then teach it some normal attack or sandstorm

Now that's a balanced team. I would rate it a 7 of 10.