With Venusaur ex already having a whopping 190 health, this will slow down your opponent as they try to land enough of a dent on your Pokemon to score points
As for Tawnos, Urzas Apprentice, well, Gavin Verhey once used him as an example in why they only do two new commanders for decks these days
Pokmon may only evolve once per turn, and may not evolve on the turn they are played
After beating a total of 16 bosses, comprising Club Masters and Team Great Rocket bosses, you face the original four Grand Masters and then two more mini-bosses until you come up to King Biruritchi himself where you have a best-of-three match
So, building around TAUC mechanics like convoke and station is a way to access game-breaking tempo plays essentially for free, as a reward for doing something which is already valuable on its own at all points of the game