These hardly seem restrictive limits to place on Volo because there are just loads of valuable options available in blue and green
Once transformed, it becomes Polukranos, Engine of Ruin, which is a 6/6 with reach and lifelink and reads: Whenever Polukranos, Engine of Ruin or another nontoken Hydra you control dies, create a 3/3 green and white Phyrexian Hydra creature token with reach and a 3/3 green and white Phyrexian Hydra creature token with lifelink. Even without any other hydra creatures, the fact this card will split into two is amazing - but with some clever deckbuilding, it could make your deck unkillable
Reunite with the Pokmon of Unova, and rise to the top as a Trainer in a land of unity and legends
This card can be tapped to allow you to draw a card and discard a card, or you can pay four mana and tap it to transform it as long as there are four or more permanent types in your graveyard
The next Swiss rounds and the Top Cut will be played thereafter