"Tekka and Pinich" is the first chapter of the Dragon Ball Fusions the Manga!!.
Tekka and Pinich spar with each other as Bulma watches. Flashing back to earlier, it is shown that Tekka and Pinich gathered the Dragon Balls and wished for the greatest tournament of all to begin. This causes Shenron to create a Valley of Time and Space above Korin Tower, so that all of the strongest fighters to have existed can participate in the Strongest in Time and Space Tournament - which requires teams of five.
The two meet Bulma, who explains the circumstances to them and gifts them each with a Time-Space Radar - which can locate powerful warriors for them to add to their tournament teams.
Back in the present, Tekka and Pinich stop sparring, ending in a draw, the two then part ways. Goten and Truks then arrive and tell Bulma that they are heading to fight some villains who have appeared, and Tekka follows along as he notes that they are powerful. The villains turn out to be Raditz and Nappa. Goten and Trunks fuse into Gotenks and engage Raditz in battle - manage to pummel him and causing Tekka to be amazed at the power of fusion, while Nappa easily overwhelms Tekka. Tekka being in trouble distracts Gotenks and allows Raditz to briefly gain the upperhand by blinding Gotenks with a ki blast, however Gotenks eventually defeats him. Tekka draws strength from his promise to win the tournament and manages to defeat Nappa.
The group then celebrate their victory, while Raditz vows that he and Nappa will try out fusion for themselves.