I've used some very weird Pokemon so I might be able to help with this. I feel any of these pokemon can be used, but ranking them is a bit hard.
Lanturn
Tier: D
Availability: Somewhat Early
Stats: Poor
Movepool: Okay
Despite it's terrible stats and shallow movepool, it's a very decent Pokemon early game. While it can't hit that hard, it gains confuse ray and charge beam. What this thing can do is take special hits like no tomorrow. If you need a wall, it's not a bad option.
Manectric
Tier: C
Availability: Very Early
Stats: Average
Movepool: Good
the biggest issue with Manetric is that it doesn't learn anything useful early and it's best moves are from TMs (Overheat). Thunder Wave combined with it's good speed is useful for halting threats. If it had a better attack stat, I'd definitely give it a higher rank.
Typhlosion
Tier: C
Availability: Very Early/Late
Stats: Average
Movepool: Poor
I was surprised by this Pokemon. While it is overshadowed by it's Fire/Fighting successors, it's not a bad Pokemon. If you need a hard hitting, speedy fire type, Typhlosion is an excellent choice.
Roserade
Tier: A
Availability: Somewhat Late
Stats: Good
Movepool: Poor
This Pokemon is great at three things: Poison, Recovering, and Hitting hard. Leech Seed and Toxic Spikes are great options as Roserade can outspeed quite a bit and the AI isn't smart enough to switch (yet). This thing can also hit like a truck with Petal Dance. The biggest downside is it's frail defense. As long as it is used wisely, it can be a great asset to almost any team.
Honchkrow
Tier: C
Availability: Varies
Stats: Average
Movepool: Good
If this Pokemon had better speed, it'd easily be an A rank. Like Crobat, it gains the ability to use Haze. With Super Luck and a Scope Lens, this bird will put a dent into some really bulky Pokemon. It'll probably take a hit or two before going down because it doesn't have the defenses to stand that long.
Toxicroak
Tier: B
Availability: Somewhat Late
Stats: Good
Movepool: Great
Toxicroak is a really special case. While it doesn't learn any great STAB moves early, it has a couple nasty little tricks up it's sleeve. Swagger, Mud Bomb, Revenge, and Sucker Punch are some of it's moves it'll learn early. It starts out rather poor, but it gains potential as the game goes on.
Escalvier
Tier: B
Availability: Late
Stats: Good
Movepool: Good
While it's no Scissor, Escalvier has some great uses. It can be used as a staller in order to heal everyone up or go on the offensive and really hurt the opponent. Another upside is that this Pokemon grows very fast meaning it's not going to lag behind despite it's late availability. He also has an advantage against all four leaders that follow him. It's a pretty good pokemon, but there are much better options.
Cherrim
Tier: C
Availability: Very Early
Stats: Varies
Movepool: Poor
On paper, this pokemon is terrible. In Reborn, it's not too bad. The biggest hindrance is that Sunny Day needs to be up which will really hurt any water types and wastes a turn in battle. Double Battles is where it really shines. Flower Gift raises the attack and special defense by 50% when it sunny of both it and it's partner. This is a very difficult pokemon to use, but it's very strong when used correctly.
Arbok
Tier: D
Availability: Very Eary
Stats: Poor
Movepool: Good
If you're going to use Arbok, it's not going to be for Attacking. With moves like Sreech, Glarce, Acid Spray, and a Poison move along with intimidate, it's good for a setup. Not the best Pokemon out there, but it has it's uses.
Alakazam
Tier: A
Availability: Late
Stats: Excelent
Movepool: Great
Alakazam used to be a great pain to get as you had to trade a Bibarel for an Abra which was worth it. Based off that experience, Alakazam is a Pokemon that'll be useful throughout the whole game. It's both fast and strong. It'll be a major pain to raise, but the reward is worth the efforts.
Emolga
Tier: D
Availability: Somewhat early
Stats: Poor
Movepool: Great
Emolga as a whole is terrible, but has a few little gimmicks that make him a little useful like acrobatics and light screen. His typing isn't too bad either, but it's his stats that hinder him to be too weak. He's very useful early, but he'll drag behind later.