Basically, that means you should expect to see it in basically every set
Pokmon Snap Contest Pikachu $270,000 Back when Pokmon Snap was first released in 1999, a contest was held to take photos of a Pokmon in-game, with the winning photo to be printed on a unique Pokmon card
In general, I would look at these two factors when looking to include cards not of your tribe's creature type: Is this creature so strong that it, on its own, is generally stronger than my tribal creatures when they are receiving bonuses and/or empowering my other cards
Thats a lot of mana
Its more redundant than it is necessary, since there are a lot of counter amplifying effects in the format already, but these decks like the consistency
Bonus: the spells that untap your attacking creatures let your vigilant beaters tap for card draw before you go back in for the kill