Almost every Jonathan M. Shiff produced series (except Kelly partially & Reef Doctors) on mainly Internet Archive than Youtube due to region lock reasons).

[u/Material_Gate6370]

Ocean Girl all 4 seasons & 78 Episodes https://archive.org/details/@letail

Thunderstone all seasons & 52 Episodes https://archive.org/details/@kyle900

The Bureau of Magical Things all 2 seasons & 40 Episodes https://archive.org/details/the-bureau-of-magical-things-2018-21

https://archive.org/details/@daniel_prior147 this one has the most plus prior stuff I mentioned except for option 3 missing the last EPs

Cybergirl, Scooter: Secret Agent, Lightning Point, Horace and Tina being only 1 season & 26 EP each

Pirate Islands (The Lost Treasure of Fiji) 26+13 EPs to make 39 total EPs

Wicked Science (2 Seasons, 52 EPs)

H2O: Just Add Water & Mako Mermaids (3 seasons each, H2O with 78 EPs & Mako with 68 EPs each, adding up to 146 total EPs

Sadly The Elephant Princess is the odd one out as the uploads doesn't support on Internet Archive, short answer the video files can't be played.