I am not really sure if Traxor's banana was made in Flash...it was like somewhat just a gif animation software or so...
Indeed, the best software to develop a flash file is
Macromedia's Flash. Powerful, many things adjustable yet that means many things to learn.
SWiSHmax is quite good if you want something easy to learn. People say SWiSH is only for text effects but I think it does many things far beyond that
There are tons of tutorials on internet so,
Google's always your friend