Sure you have no problem running melee, but take a look at the
Dolphin CPU benchmark and you'll see that AMD chips undoubtedly perform worse in Dolphin, it's not because I have a preference for Intel, but it is how Dolphin works. It can only use two CPU cores and AMD CPU's falter in singlethreaded performance. Look at any CPU benchmark elsewhere and you can confirm this. Just because you don't have any problems doesn't mean that's what you should get.
To run melee online as smooth as possible you'd be fine with the G3258 and any decent graphics card.. I just don't think it's a good idea to buy budget parts that will be outdated and obsolete in a year just because it will run what you want to play at this point in time. That's why I recommend those parts a little over budget. They will last much longer in terms of relevancy in the long run.