"That was too Easy." phrase Very simple, the phrase is a sort of mocking one that you would say to someone else, implying that it was no challenge to you at all. Example, a friend challenges you to a game of chess and you win rather easily,
“That was too Easy.”  can simply be translated as "那也太容易了" 

However, in a mocking manner, you can say: 

不外如是 (It is unimpressive)-- It is a very insulting phrase, saying that is to look down upon someone

這就完了? (just like this, you are finished?) --implying the other guy cannot provide tougher challenge to you