Yes, the real Ansem (Ansem the Wise) was a good guy. He was just confused with the idea of getting revenge on his apprentice, Xehanort. Xehanort had stolen the idea of studying and using hearts for...
There was no Ansem in Kingdom Hearts 358/2 Days. However, there was Riku-Ansem (Riku's dark side) but Riku was still a good guy. In the other games, Ansem the Wise is a bad guy.
Ansem the Wise is the real Ansem, who studied Heartless in Radient Garden until his apprentices accidentally became Heartless.The villain that we know as Ansem is actually the Heartless of Xehanort....
Ansem the Wise, is the original Ansem, in KH 1 the Ansem they go by is a heartless, with the replica of his understudy, who is the same as Xeanhort from KH 2, Ansem the Wise is the Ansem that made...