>>34376458Fire Red and Leaf Green are enhanced remakes of the first Pokemon games. They are still pretty basic in terms of gameplay, which should give you an idea of whether or not you want to continue investing your time in the series.
From there, if you want to continue on a rather natural progression and sample what's considered one of the best pair of games in the franchise, try Heart Gold or Soul Silver.
If you just want to be caught up to speed, just jump to Ultra Sun or Ultra Moon. Pretty much the only thing you'll miss if you do that is the introduction of Mega evolutions within the main adventure, which was the main gimmick of X and Y, the last original pair of games.
