"喜羊羊" is a pun, because it has same pronunciation as "喜洋洋” which means "pleasant,happy,radiant, ect". 羊 can refer to goat(山羊) or sheep(绵羊) here in China, I am not that interested in this cartoon enough to find out weather those 羊 are goat or sheep. 灰太狼，灰=grey. 太狼 is also a pun, besides the meaning of "big wolf", it has the other meaning as "太郎" because of same pronunciation.

It's a hero's name in a Chinese cartoon And he is a sheep.I'm afraid that xi doesn't mean pleasant.maybe it's just a pronunciation.but people can think he is a happy sheep.it doesn't matter.😂