Is Deoxys a good Pokemon

Answer 1

My opinion is yes. I think it's a very good and rare pokemon. But the problem with Deoxys is about the moves it learns. Here's what I mean (Note: You catch Deoxys on Birth Island, at 30 lv.):

At 33 levels, Deoxys learns Pursuit.

At 41 levels, Deoxys learns Psychic.

At 49 levels, Deoxys learns Snatch.

At 57 levels, Deoxys learns Psycho Shift.

At 65 levels, Deoxys learns Zen Headbutt.

At 73 levels, Deoxys learns Cosmic Power.

At 81 levels, Deoxys learns Recover.

At 89 levels, Deoxys learns Psycho Boost.

And last, at 97 levels, Deoxys learns Hyper Beam.

See? If you check it out by yourself, you'll see that there is only a small amount of moves that are good enough for Deoxys to be taught (Psychic, Zen Headbutt, Psycho Boost and maybe Recover). Hope I helped :)