Gift of Doom Gift of DoomGift of Doom seems to me like a decent method of going about alternative costs
Always respect Pokemon Company's intellectual property rights
These creatures are yours for as long as Nihiloor is in play, which gives you plenty of time to sacrifice them to prevent your opponents from regaining control
Cat Tribal isn't particularly powerful - especially not in Commander, where go-wide weenie decks just don't get you there, but you can do some dumb things with Felidar Guardian if you're looking for some infinite combos and they can potentially trigger this guy's token generation for infinite cat tokens
Choose from Unfinished Wood, Black, Grey, Red, Hot Wheels Blue, or White (not shown)
The end result is a deck that can do some absurdly powerful things really quickly