Yoshi is Mario and Luigi's best friends of the Mario franchise and helps along their quests on many occasions. Often having to rescue them.
In SMBZD: Two World's Fate, Yoshi is a main character and easily does well with teaming up with Sonic. He is happy to reunite with the Yoshi herd and enjoys fighting with sonic to defeat Froggy. He develops many transformations that are stronger than some of Mario's.
Yoshi has a handful of techniques and many transformations that he does not use yet until episode 10 where he uses the Hammer Bros. item and turns into Hammer Yoshi. See Yoshi-Transformations for more information about this.