Roselia is available in all of the Hoenn, Sinnoh, and Kalos games. It also makes an appearance in the Unova sequels and the Johto remakes (post-Elite Four in the latter). It is available in Alola-based games via Island scan on Ula'ula Island in Ula'ula Meadow on Wednesday.
Roserade is available in all of the aforementioned games except for Ruby, Sapphire, and Emerald. Budew is only available in the Sinnoh and Kalos games.
Completed analyses of the Budew line so far: