How to translate Pinyin with tones marks on Google Translate?
Google Translate did not support translating with Pinyin to Other language, simply input ni hao only lead to google suggesting the best matching chinese words for ni hao then translate it using the suggested best words to the language you selected. 

Try to input the pinyin of chinese word with 同音不同字(Sounds same but different words) example: 星星 and 猩猩

Google Translate only will suggest you 星星 but not 猩猩. 



Conclusion, you cannot use Pinyin with tones in Google Translate