Scorewise, aiming only for blue UFO's is the best course of action.NO; a balance between Blue and Rainbow is actually recommended even by Touhou Wiki, particularly a lot of rainbows in the late stages, due to the extra UFO that is obtained from them and their item conversion.
As the critical UFO summoning spots (over 100 point/power items during a single UFO's lifetime) don't start until post-midboss stage 3, it is generally advised to maximize the point value until that point using all means available (on Easy mode, it is possible to increase the value up to as much as 37,000 upon reaching the stage 3 boss). Collecting a single UFO token while a UFO is already summoned is equivalent to 1000 graze points, and can be done within the first minute of stage 1. Because of this, Blinking UFOs are significantly better for scoring in early stages than Blue UFOs, as on satiation a Blinking UFO will release a UFO token that can be immediately collected to increase the point value by another 1000.Also, when Rainbow UFOs receive Power Items, they get converted to Point Items instead, so you can take advantage of the Rainbow's multipler for that too, unlike Blue ones which still retain Power as Power. Take note though that Point Items get converted to Power, but there's an immense amount of Power Items in this game, especially in the late stages.
A quick rule of thumb here is try to minimalize UFO summon on stage 1 to 4, and to summon Blue or Rainbow UFO as much as you can on stage 5 and 6.
Speaking about survival: Also, one thing that's actually pleasing to do in TH12 is overbombing, as it's made even more possible by Green UFOs. The wiki has some input on this too, and is still up to preference:
For survival
Green and red UFOs, while generally useless in high score runs, are able to provide a less experienced player with a sufficient life and bomb supply, as well as clear the screen of bullets in a bomb-like fashion. Be wary that they should still be satiated with items before destruction in order to take full advantage of their summoning.
Also note that it is slightly more beneficial to summon green UFOs compared to red:
* 1 green UFO = 1.33 bombs. 1 red UFO = 0.5 lives.
* Each green UFO gives at least one immediately useful full bomb item.
* 6 green UFOs = 8 bombs. 6 red UFOs = 3 lives (6 full bombs).
* If a player uses all of their bombs before dying, going for green UFOs potentially gives them 33% more full bombs.
* Note, however, that dying will also clear the screen of bullets. Thus, a player who has summoned 6 red UFOs can fail to dodge 9 times compared with the green player's 8. This is usually a less attractive option because of power loss and reduced versatility.
Barring some exceptions, a character's bomb is generally powerful enough to quickly deplete the HP of most spellcards. By methodically summoning green UFOs, a player should be able to bomb through (nearly) every problematic attack, allowing an easier victory. Green UFOs also allow a marginally better score increase, although it's pointless to use them for that purpose. However, if a player is inexperienced with both deciding a good bombing opportunity and using bombs reactively (deathbombing), going for red UFOs instead may have its merit.
(you'll need at least 60 in the Results->Spell Cards record page) Trust me, since you've cleared Extra, Phantasm wouldn't take too long to clear.
