Even the flavor text helps out here, citing a salient line from the story
5 Slowbro Unbroken Bonds (43/214) When it comes to instant win conditions, you probably want yourself to win, right
Unlike many planeswalkers the ultimate on Ajani creates a secure lock on the game, and thanks to the protection Ajani's ability gives, it is practical to get there even against decks capable of attacking
When using fusion, there are GY recovery and special summon from his GY, so recovery can be done, but after all the name difference of each material is painful
An unfavorable matchup would be against decks capable of using many techs, like Mathmech for example, which besides interrupting your combo with handtraps, has a good ability to finish the game through an otk