Exiling a card with suspend isn't casting that card
There are likely a number of dragons that were of similar relative strength to Rith, the Awakener over the years, but Rith, the Awakener got its moment while those others did not
A quick search of Scryfall reveals over 850 instances of the text "at the beginning of your upkeep," so there's a plethora of options when producing a Commander deck based around upkeep triggers
It is filled with new Pokmon, new friends, and so much fun
But no, its just the owners being creative with the tools at their disposal
The vast majority of Tera Pokmon have normal typing, normal resistances/weaknesses, and just have scrambled up energy requirements, needing a bunch of different energy types