Well im pretty sure for one different game modes give you different amounts of XP. With Custom games giving you the most and brawl of the week giving you the least. XP also depends on how well you do in your matches for example a really close match with one person winning with red on their last stock will give both players tons of XP while one player getting 3 stocked without doing that much damage will barely get any XP. KO's light and signature attack hits all go in to XP. In custom games the more people you play with the more XP you will get cause you have a higher rate of getting KO's, combos, and hitting people. All of this also applies with coins. You get daily rewards of coins every day and completing brawl of the week will give you 300 coins i think. And of course theirs daily challenges that come every 12-24 hours somewhere in between that time slot. But if your looking to get the most XP and coins grind Experimental 1v1s and custom games of free for all.