I'd say the best place to start when getting MM games to compete in would be to search amazon.com or a local EB Games, Game Crazy, Game Stop, etc. In terms of what games to start with, I recommend Mega Man X Collection (get X5, X6, and Battle & Chase). In terms of being TA friendly, X8 is probably the best in that regard. The Zero series is also really good for time attacking, but I strongly suggest getting some experience with the X series first since the Zero series can be brutally challenging (that series was designed with the hardened veterans of the MM franchise in mind). However, IMO, the Zero series in terms of gameplay and fun is the best bet (along with Mega Man Powered Up) in terms of what games are availible for competition.