Turning or into a hand of six cards is always going to be great, and Crobat V will matter to competitive players for a long time
It gets even better if you have ways to untap it and create tokens during your foes' turns
That way, when Niv-Mizzet Reborn collects two-color cards from the top of the library, most of them will be proper graveyard fodder for Niv-Mizzet, Supreme
Although Card not found costs four and is thus not very efficient at ramping, it does have a significant advantage in Commander and has seen some play in Modern, where you can find a shock dual with it
Once transformed into Crystallized Serah, the +2/+2 to all your legendary creatures is something that makes it incredibly hard for your opponent to catch up to you
Haxorus' first attack does not deal much damage, but it is an intriguing way to lower the HP of evolution Pokmon so that they can be knocked out on following turns by stronger attacks