At the start of Season 1 with Winx characters these are the ages for characters that make their first appearance-
Sky, Diaspro, Tecna, Timmy, and Stormy are 16.
Flora, Musa, Riven, and Darcy are 15.
Stella, Brandon, and Icy are 17.
Daphne is 24.
Perla(oc) is 21.
Siena(oc) is 20.
Alec(oc) is 22.
Season 2 ages for characters that make first appearance are-
Helia is 16.
Aisha is 17.
Season 3 ages for characters that make first appearance are-
Nabu is 18.
Chimera is 12.
Valtor is 26.
Season 4 ages for characters that make first appearance are-
Roxy is 15.
Selina is 16.
Side note- I switched Luke and Annabeth's roles/ages for the PJO series for a reason. So Luke is now 16 like Percy and Annabeth is 19 like cannon Luke. This also means that Annabeth is working with Kronos, not Luke.
Another side note- I'm changing something from canon winx as well. Sky ended his forced engagement to Diaspro before season 1 starts in this series.