It looks like Mario Tennis Aces is set to receive some post-launch updates in the form of new characters this year. Nintendo confirmed during their Treehouse E3 stream that Koopa Troopa and Blooper will be hitting the court in July and August, respectively. Both will be available as a free software update, so you won’t need to shell out any coin to give them a spin.
I suppose these guys coming to the game means we could eventually see Shy Guy’s grand return. I don’t think it would be Mario Tennis without him dancing around the court and chanting.
Source: Destructoid Koopa Troopa and Blooper will be coming to Mario Tennis Aces as free DLC