Location
	To acquire Doomtrain, you will need to get the Solomon Ring from tears point. Once you get the ring, you will need to get 6 of the following items: Steel Pipes, Malboro Tentacles, Remedy+ Potions. After getting these items, you can summon Doomtrain, without even having to fight him.

Doomtrain
	Elemental: Poison
	Attack: Runaway Train
	Level		HP		Atk. Power
	1		-		-
	10		-		-
	28		2521		1931
	30		2686		2028
	40		3514		2509
	50		4350		2990
	60		5194		3471
	70		6046		3953
	80		6906		4434
	90		7774		4915
	100		8650		5396

Ability	AP	Opens		Ability	AP	Opens
ELEM-ATK-J	LEARNED	None		SUMMAG+10%	40	SUMMAG+20%
ST-ATK-J	Learned	None		SUMMAG+20%	70	SUMMAG+30%
ELEM-DEFx4	180	None		SUMMAG+30%	140	SUMMAG+40%
ST-DEF-Jx4	180	None		SUMMAG+40%	200	None
Magic	Learned	None		GFHP+10%	40	GFHP+20%
GF	Learned	None		GFHP+20%	70	GFHP+30%
Draw	Learned	None		GFHP+30%	140	GFHP+40%
Item	Learned	None		GFHP+40%	200	None
Darkside	100	None		Boost	10	None
Absorb	80	None		Junk Shop	Learned	None
Auto-Shell	250	NONE		Forbid Med-RF	200	None

With the different status effects of Doomtrain, it is worth casting. Even if the enemies are immune to the Poison attacks. The statuses inflicted include: Dark, Sleep, Silence, Berserk, Doom, Petrify, and Vit-0. Vit-0 is extremely useful in the end game bosses, when magical defenses are high. It connects far more often than Meltdown.
Doomtrain's most useful abilities is the ST-DEF-Jx4, and the ELEM-DEFx4. With these in place, you can make your character absorb all elemental attacks, as well as provide defense for most status effects. Junk Shop allows you to upgrade weapons, without having to go to a town. This is very useful on Disk 4, when towns are not accessible.