Bidoof is your best bet for HM slave really easy to get early on, vivillion again obtainable early gothitelle available just before the 3rd gym its a hide and seek event do not win the gym battle untill you got the gothitelle because you wont get another chance to get it , the last location of gotheitelle is near the exit, rock smash is the most needed hm and then surf after that, as for your fifth i would suggest a strong dark type for the fourth gym because that will be pretty difficult with gothitelle its simply not strong enough to take a hit from them or possibly a xatu which was pretty effective against the 4th gym, Roserade is a real pain to get with a terrible encounter rate for budew and with only 1 link heart available pretty late you might be struggling to get it ( i think it needs a link stone its not a pokemon ive ever used lol) my suggestion for the dark type would be houndoom but your team seems pretty grass orientated so maybe a water type might be better for you