This unassuming rodent, printed in Return to Ravnica, basically required an immediate answer, or it would multiply out of control, each copy making the rat horde, and the rats themselves, grow bigger and bigger
X: 1% Trainers / Supporters / Stadiums / Energy: 37% Items: 13% Supporters: 10% Tools: 3% Ace Spec: 1% Stadiums: 5% Special Energy: 5% If you're going to pick a different number of cards, I would go with ones that are divisible by 6, 8, 10, and 12
Control is the same old hodgepodge of "basically any jumble of removals, counters, draw, and finishers will do" but aggro has neon lights over it like " GO THIS WAY "
It was the most widely played, and arguably the most efficient companion
It can even occasionally be a planeswalker, but only very specific ones, so its usually best to just stick to creatures