SMT-DDR now hosts a dedicated TvC server. The server is fast at making matches, but connection lag depends on users setup/location. Once a connection is made the matches are p2p. The link is to an FAQ and "how to set up" site. The server handles Wii and WiiU, and I'm pretty sure dolphin users can access as well. If any dolphin users want to connect the dns is
Right now the server is accessed by Riivolution. There is no homebrew app.
Free battle works, Ranked battle works.