Which 1999 Tekken title is the non-canon tag-team entry released before Tekken 4?

The 1999 non-canon tag-team Tekken title released before Tekken 4 is Tekken Tag Tournament.

Developed and published by Namco, Tekken Tag Tournament began as an arcade game and later became a PlayStation 2 launch title in North America and Europe in 2000. Rather than continuing the main storyline, it brought together fighters from earlier Tekken games in a celebratory crossover.

Its defining feature was two-on-two combat. Players selected a pair of fighters and could tag between them during a match, allowing the resting character to recover some health. This system also created new combo opportunities and strategic risks, since an opponent could exploit a vulnerable character waiting off-screen.

The title is often confused with Tekken Tag Tournament 2, released in 2011, or with later portable and downloadable spin-offs. Tekken 3D: Prime Edition and Tekken Advance are separate projects, while Tekken Revolution arrived much later as a free-to-play digital game. Tekken Tag Tournament is the bridge between Tekken 3 and Tekken 4 in release history, but not in canonical plot.