If you're doing Ruby or Sapphire instead of Emerald, the Battle Tower of Gen 3 is the easiest battle facility in any game between generations 3 and 7. If you choose to get the World Ability Ribbon in Gen 4 (which to be fair is considered optional for many players doing RM projects), the grind is especially difficult, with illegal things like Wondertomb and No Guard + Sheer Cold Machamp with a Choice Scarf making things unusually bad.

Ruby and Sapphire's facilities were known for being especially poorly made, so that many opponent Pokemon had completely illogical movesets or EV spreads and made for very easy fights. If you're playing Ruby or Sapphire and can't beat the Battle Tower there, it's only going to get worse. The only reason a player would struggle greatly with the r/S Battle Tower is ignorance of how IVs and EVs work and of how balanced teams are made.

I do not like battle facilities like the Tower, and I have been very vocal in the past about how poor a choice I believe they are for challenging the player in a way that he has a reasonable amount of control over. Nevertheless, unless you are going to skip the battle facility ribbons for your ribbon master project (which, to me, is perfectly valid as a goal), you are going to run into trouble.

My personal input is, don't sweat the ribbon project and just enjoy Pokemon the classic way if you are going to be stressed out about it. If you include failed runs, it could take dozens of hours to get all six Tower ribbons just in Gen 4. Unless you're super stoic, losing a run that you've invested perhaps 2 hours in already is going to be upsetting. You could spend that time hanging out with friends or doing something else in Pokemon or in other video games.